3.2 Evaluating Expressions

3.2 Evaluating Algebraic Expressions

​Think about our example from Monday with the cap and shirts.
When we bought 1 cap and n shirts the cost was
$(10+8n). Now what would the cost be if we bought 9 shirts?

We will replace the n with an 8: $[10 + 8(9)].
This will give us a total cost of: $[10 + 72] = $82

This process of replacing a variable with its value to find the exact value of an expression is called substitution.

Math Response

Now its your turn, Try It a from your notes:

When x = 5 and y = 2, find the value of

2x - 7y

Type answer here

Correct Answer: -4

Deg^°

Rad

Math Response

Now its your turn, Try It b from your notes:

When x = 5 and y = 2, find the value of

$$xy^2-3xy+10$$

Type answer here

Correct Answer: 0

Deg^°

Rad

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Multiple Choice

When $$x=\frac{3}{4}$$ , y = 4 and z = -1, evaluate the following:

$$z\left(8x+yz\right)$$

• -2

• -8

• 8

• 4

Multiple Choice

When $$x=\frac{3}{4}$$ , y = 4 and z = -1, evaluate the following:

$$\frac{10xy-z+2}{xy^2-3}$$

• $$\frac{3}{11}$$

• $$\frac{11}{3}$$

• $$\frac{31}{9}$$

• $$\frac{9}{31}$$