9G (2.9) Plugging in the value of a variable

(2.9)
Plugging in the value of a variable

We said that a variable is a number whose value varies based on the situation. We use a letter to represent it
ex. x = 2 , x is a variable. It's value is 2 right now

The two common ways we will see variables are:

Multiple Choice

x = 1

Plug the value of x into the expression:

$$x+4$$

What was the value of the expression?

• 1 + 4 = 6

• 1 + 4 = 4

• 1 + 4 = 5

• We can't know the value of the expression because there's no equal sign

Multiple Choice

x = 3

Plug the value of x into the expression:

$$x+9$$

What was the value of the expression?

• 3 + 9 = 15

• 3 + 9 = 12

• 3 + 9 = 9

• We can't know the value of the expression because there's no equal sign

Multiple Choice

x = 2

Plug the value of x into the expression:

$$3+x$$

What was the value of the expression?

• 3 + 2 = 5

• 3 + 2 = 4

• 3 + 2 = 3

• We can't know the value of the expression because there's no equal sign

Multiple Choice

x = 11

Plug the value of x into the expression:

$$x+13$$

What was the value of the expression?

• 11 + 13 = 24

• 11 + 13 = 11

• 11 + 13 = 13

• We can't know the value of the expression because there's no equal sign

• 11 + 13 = 23

Multiple Choice

x = 7

Plug the value of x into the expression:

$$x+13$$

What was the value of the expression?

• 7 + 13 = 24

• 7 + 13 = 7

• 7 + 13 = 13

• We can't know the value of the expression because there's no equal sign

• 7 + 13 = 20

Multiple Choice

x = 20

Plug the value of x into the expression:

$$x+13$$

What was the value of the expression?

• 20 + 13 = 33

• 20 + 13 = 20

• 20 + 13 = 13

• We can't know the value of the expression because there's no equal sign

• 20 + 13 = 20

Multiple Choice

x = 12

Plug the value of x into the expression:

$$x-2$$

What was the value of the expression?

• 10

• 12

• 2

• We can't know the value of the expression because there's no equal sign

• -2

Multiple Choice

x = 5

Plug the value of x into the expression:

$$x-5$$

What was the value of the expression?

• 0

• 5

• -5

• We can't know the value of the expression because there's no equal sign

• 1

Multiple Choice

x = 10

Plug the value of x into the expression:

$$x-15$$

What was the value of the expression?

• 0

• 10

• -5

• We can't know the value of the expression because there's no equal sign

• 5

Multiple Choice

x = 1

Plug the value of x into the expression:

$$x-4$$

What was the value of the expression?

• 0

• -3

• 1

• We can't know the value of the expression because there's no equal sign

• -4

Multiple Choice

x = 4

Plug the value of x into the expression:

$$10-x$$

What was the value of the expression?

• 0

• 6

• 4

• We can't know the value of the expression because there's no equal sign

• 10

Multiple Choice

x = 1

Plug the value of x into the expression:

$$10-x$$

What was the value of the expression?

• 0

• 9

• 1

• We can't know the value of the expression because there's no equal sign

• 10

Multiple Choice

x = 11

Plug the value of x into the expression:

$$10-x$$

What was the value of the expression?

• 0

• 1

• 11

• We can't know the value of the expression because there's no equal sign

• -1

Multiple Choice

x = 17

Plug the value of x into the expression:

$$17-x$$

What was the value of the expression?

• 0

• 1

• 11

• We can't know the value of the expression because there's no equal sign

• -1

Multiple Choice

x = -3

Plug the value of x into the expression:

$$x+4$$

What was the value of the expression?

• 4

• 1

• -3

• We can't know the value of the expression because there's no equal sign

• -1

Multiple Choice

x = -7

Plug the value of x into the expression:

$$x+4$$

What was the value of the expression?

• 4

• 1

• -3

• We can't know the value of the expression because there's no equal sign

• -7

Multiple Choice

x = -7

Plug the value of x into the expression:

$$x+7$$

What was the value of the expression?

• 4

• 0

• 7

• We can't know the value of the expression because there's no equal sign

• -7

Multiple Choice

x = -7

Plug the value of x into the expression:

$$x-7$$

What was the value of the expression?

• -14

• 0

• 7

• We can't know the value of the expression because there's no equal sign

• -7

Multiple Choice

x = -2

Plug the value of x into the expression:

$$x-8$$

What was the value of the expression?

• -10

• 10

• -2

• We can't know the value of the expression because there's no equal sign

• -8

Multiple Choice

x = 2

Plug the value of x into the expression:

$$3\left(x\right)$$

What was the value of the expression?

• 3(2) = 3

• 3(2) = 6

• 3(2) = 2

• We can't know the value of the expression because there's no equal sign

• 3(2) = 5

Multiple Choice

x = 2

Plug the value of x into the expression:

$$5\left(x\right)$$

What was the value of the expression?

• 5(2) = 5

• 5(2) = 10

• 5(2) = 2

• We can't know the value of the expression because there's no equal sign

• 5(2) = 7

Multiple Choice

x = 4

Plug the value of x into the expression:

$$5\left(x\right)$$

What was the value of the expression?

• 9

• 20

• 4

• We can't know the value of the expression because there's no equal sign

• 5

Multiple Choice

x = 21

Plug the value of x into the expression:

$$3\left(x\right)$$

What was the value of the expression?

• 63

• 3

• 21

• We can't know the value of the expression because there's no equal sign

• 24

Multiple Choice

x = 9

Plug the value of x into the expression:

$$x\left(2\right)$$

What was the value of the expression?

• 18

• 11

• 2

• We can't know the value of the expression because there's no equal sign

• 9

Multiple Choice

x = 3

Plug the value of x into the expression:

$$4x$$

What was the value of the expression?

• 12

• 7

• 4

• We can't know the value of the expression because there's no equal sign

• 3

Multiple Choice

x = 3

Plug the value of x into the expression:

$$5x$$

What was the value of the expression?

• 15

• 8

• 5

• We can't know the value of the expression because there's no equal sign

• 3

Multiple Choice

x = 3

Plug the value of x into the expression:

$$7x$$

What was the value of the expression?

• 21

• 10

• 7

• We can't know the value of the expression because there's no equal sign

• 3

Multiple Choice

x = 3

Plug the value of x into the expression:

$$12x$$

What was the value of the expression?

• 36

• 15

• 12

• We can't know the value of the expression because there's no equal sign

• 3

Multiple Choice

x = 10

Plug the value of x into the expression:

$$\frac{x}{2}$$

What was the value of the expression?

• $$\frac{10}{2}=$$ 5

• $$\frac{10}{2}=$$ 2

• $$\frac{10}{2}=$$ 10

• We can't know the value of the expression because there's no equal sign

• $$\frac{10}{2}=$$ 3

Multiple Choice

x = 9

Plug the value of x into the expression:

$$\frac{x}{3}$$

What was the value of the expression?

• $$\frac{9}{3}=$$ 3

• $$\frac{9}{3}=$$ 9

• $$\frac{9}{3}=$$ 12

• We can't know the value of the expression because there's no equal sign

• $$\frac{9}{3}=$$ 6

Multiple Choice

x = 8

Plug the value of x into the expression:

$$\frac{x}{2}$$

What was the value of the expression?

• 4

• 2

• 8

• We can't know the value of the expression because there's no equal sign

• 3

Multiple Choice

x = 15

Plug the value of x into the expression:

$$\frac{x}{3}$$

What was the value of the expression?

• 3

• 5

• 15

• We can't know the value of the expression because there's no equal sign

• 10

Multiple Choice

x = 3

Plug the value of x into the expression:

$$\frac{x}{3}$$

What was the value of the expression?

• 3

• 1

• 6

• We can't know the value of the expression because there's no equal sign

• 9

Multiple Choice

x = 7

Plug the value of x into the expression:

$$\frac{x}{3}$$

What was the value of the expression?

• 3

• 1

• 6

• We can't know the value of the expression because there's no equal sign

• $$\frac{7}{3}$$

Multiple Choice

x = 1

Plug the value of x into the expression:

$$2x\ +3$$

What was the value of the expression?

• 3

• 5

• 6

• We can't know the value of the expression because there's no equal sign

• 4

Multiple Choice

x = 3

Plug the value of x into the expression:

$$2x\ +3$$

What was the value of the expression?

• 3

• 9

• 6

• We can't know the value of the expression because there's no equal sign

• 18

Multiple Choice

x = 10

Plug the value of x into the expression:

$$2x\ +3$$

What was the value of the expression?

• 23

• 20

• 3

• We can't know the value of the expression because there's no equal sign

• 15

Multiple Choice

x = 2

Plug the value of x into the expression:

$$4x\ +5$$

What was the value of the expression?

• 13

• 20

• 3

• We can't know the value of the expression because there's no equal sign

• 15

Multiple Choice

x = 2

Plug the value of x into the expression:

$$3+3x$$

What was the value of the expression?

• 6

• 9

• 8

• We can't know the value of the expression because there's no equal sign

• 12

Multiple Choice

x = 3

Plug the value of x into the expression:

$$5+2x$$

What was the value of the expression?

• 10

• 11

• 7

• We can't know the value of the expression because there's no equal sign

• 12

Multiple Choice

x = 2

Plug the value of x into the expression:

$$3x-4$$

What was the value of the expression?

• 2

• 5

• 4

• We can't know the value of the expression because there's no equal sign

• 1

Multiple Choice

x = 1

Plug the value of x into the expression:

$$4x-4$$

What was the value of the expression?

• 0

• 1

• 4

• We can't know the value of the expression because there's no equal sign

• 2

Multiple Choice

x = 2

Plug the value of x into the expression:

$$4x-4$$

What was the value of the expression?

• 0

• 1

• 4

• We can't know the value of the expression because there's no equal sign

• 2

Multiple Choice

x = 8

Plug the value of x into the expression:

$$\frac{x}{4}+1$$

What was the value of the expression?

• 3

• 1

• 4

• We can't know the value of the expression because there's no equal sign

• 2

Multiple Choice

x = 4

Plug the value of x into the expression:

$$\frac{x}{2}+3$$

What was the value of the expression?

• 3

• 1

• 4

• We can't know the value of the expression because there's no equal sign

• 5

Multiple Choice

x = 5

Plug the value of x into the expression:

$$\frac{x}{2}+4$$

What was the value of the expression?

• $$\frac{9}{2}$$

• $$\frac{5}{2}$$

• $$\frac{5}{3}$$

• We can't know the value of the expression because there's no equal sign

• $$\frac{13}{2}$$

Multiple Choice

x = 2

Plug the value of x into the expression:

$$x^2$$

What was the value of the expression?

• 3

• 1

• 4

• We can't know the value of the expression because there's no equal sign

• 2

Multiple Choice

x = 2

Plug the value of x into the expression:

$$x^3$$

What was the value of the expression?

• 8

• 6

• 4

• We can't know the value of the expression because there's no equal sign

• 2

Multiple Choice

x = -3

Plug the value of x into the expression:

$$x^3$$

What was the value of the expression?

• 27

• -27

• 9

• We can't know the value of the expression because there's no equal sign

• -9

Multiple Choice

x = -3

Plug the value of x into the expression:

$$x^2$$

What was the value of the expression?

• 9

• -9

• 6

• We can't know the value of the expression because there's no equal sign

• -6

Multiple Choice

x = 1

Plug the value of x into the expression:

$$2x^2$$

What was the value of the expression?

• 2

• 4

• 3

• We can't know the value of the expression because there's no equal sign

• 1

Multiple Choice

x = 3

Plug the value of x into the expression:

$$5x^2$$

What was the value of the expression?

• 45

• 15

• 225

• We can't know the value of the expression because there's no equal sign

• 8

Multiple Choice

x = 4

Plug the value of x into the expression:

$$-2x^2$$

What was the value of the expression?

• -32

• 32

• -8

• We can't know the value of the expression because there's no equal sign

• 8

Multiple Choice

x = 2

Plug the value of x into the expression:

$$7x^2$$

What was the value of the expression?

• 28

• 21

• 11

• We can't know the value of the expression because there's no equal sign

• 14

Multiple Choice

x = 4

Plug the value of x into the expression:

$$x^2+1$$

What was the value of the expression?

• 17

• 16

• 9

• We can't know the value of the expression because there's no equal sign

• 5

Multiple Choice

x = 3

Plug the value of x into the expression:

$$x^2+5$$

What was the value of the expression?

• 14

• 11

• 8

• We can't know the value of the expression because there's no equal sign

• 5

Multiple Choice

x = 3

Plug the value of x into the expression:

$$x^2+5$$

What was the value of the expression?

• 14

• 11

• 8

• We can't know the value of the expression because there's no equal sign

• 5

Multiple Choice

x = 4

Plug the value of x into the expression:

$$x^2-3$$

What was the value of the expression?

• 13

• 16

• 5

• We can't know the value of the expression because there's no equal sign

• 12

Multiple Choice

x = 5

Plug the value of x into the expression:

$$x^2-9$$

What was the value of the expression?

• 13

• 16

• 5

• We can't know the value of the expression because there's no equal sign

• 12

Multiple Choice

x = 3

Plug the value of x into the expression:

$$x^2+x-10$$

What was the value of the expression?

• 2

• 12

• 3

• We can't know the value of the expression because there's no equal sign

• 10

Multiple Choice

x = 4

Plug the value of x into the expression:

$$x^2+3x+2$$

What was the value of the expression?

• 2

• 30

• 3

• We can't know the value of the expression because there's no equal sign

• 28

Multiple Choice

x = 2

Plug the value of x into the expression:

$$x^2+3x+2$$

What was the value of the expression?

• 2

• 30

• 3

• We can't know the value of the expression because there's no equal sign

• 12

Multiple Choice

x = 4

Plug the value of x into the expression:

$$x^2-2x+5$$

What was the value of the expression?

• 4

• 13

• 14

• We can't know the value of the expression because there's no equal sign

• 5

Multiple Choice

x = 3

Plug the value of x into the expression:

$$3x^2-4x+2$$

What was the value of the expression?

• 5

• 17

• 14

• We can't know the value of the expression because there's no equal sign

• 12

Multiple Choice

x = 4

Plug the value of x into the expression:

$$7x^2-3x-6$$

What was the value of the expression?

• 100

• 17

• 94

• We can't know the value of the expression because there's no equal sign

• 10