Intro to Algebra

Intro to Algebra

By Victoria Robinson

Algebra is a language.

• In many ways, learning algebra is much like learning any other language.

• You will need to know how to translate plain English into math and math into plain English. ​​

Intro to Algebra | Robinson​

• In algebra, a letter is often used to stand for a number.

• The letter used ​to stand for a number is called a variable.

  • Some common letters used as variables​ are x, y, z, a, b, c, and n. ​

• When a letter is used to stand for a number, the number is unknown. Think of those letters as "mystery numbers."

Intro to Algebra | Robinson

Multiple Choice

Which of the following expressions has a variable?

• $$x+19$$  

• $$2^2$$  

• $$6+9$$  

• $$2\left(1-4\right)$$  

Multiple Choice

Which of the following expressions has a variable?

• $$16-5$$  

• $$14+3n$$  

• $$2\cdot4\left(1+3\right)$$  

Multiple Choice

What is the variable in the following expression?

$$2\left(y+7\right)$$  

• $$7$$  

• $$2$$  

• $$y$$  

Multiple Choice

What is the variable in the following expression?

$$23+2x$$  

• 23

• 2

• $$2x$$  

• $$x$$  

• ​A variable can be a part of an expression, an equation, or an inequality.

• An expression is part of a mathematical sentence, just as a phrase is ​part of an English sentence.

  • 2n + 4 ; 3y ; 6 + x

• A mathematical sentence ​contains two expressions joined by an equal sign or an inequality sign.

  • 2h + 4 ≥ 13​ ; p + 4 = 9

• An equation is a mathematical sentence in which two expressions are joined by an equal sign. ​

  • ​c - 8 = 1 ; 4t + 9 = 17

Intro to Algebra | Robinson

Multiple Select

Select all the expressions.

• $$9x<18$$  

• $$2d$$  

• $$c=3$$  

• $$4t-4$$  

Multiple Select

Select all the expressions.

• $$3x-8$$  

• $$4c$$  

• $$2x>6$$  

• $$8+y$$  

Multiple Select

Select all the expressions.

• $$a-4$$  

• $$5y$$  

• $$4d+6=26$$  

• $$18<p+9$$  

Multiple Choice

Is the following an expression or an equation?

$$2x-4$$  

• an expression

• an equation

Multiple Choice

Is the following an expression or an equation?

$$5f+20=30$$  

• an expression

• an equation

Multiple Choice

Is the following an expression or an equation?

$$x=14$$  

• an expression

• an equation

• ​An inequality is a mathematical statement in which two phrases are joined by an inequality symbol.

  • < "less than"

  • > "greater than"

  • ≤ "less than or equal to"

  • ​≥ "greater than or equal to"

  • ​Examples:

    • 3a < 9 ; f ≥ 4

Intro to Algebra | Robinson

Multiple Choice

Is the following an equation or an inequality?

$$4t<92$$  

• equation

• inequality

• neither

Multiple Choice

Is the following an equation or an inequality?

$$x=5$$  

• equation

• inequality

• neither

Multiple Choice

Is the following an equation or an inequality?

$$7+y\le9$$  

• equation

• inequality

• neither

Multiple Choice

Is the following an equation or an inequality?

$$5z$$  

• equation

• inequality

• neither

Multiple Choice

Which symbol means "greater than"?

• $$<$$  

• $$=$$  

• $$>$$  

• $$\ge$$  

Multiple Choice

Which symbol means "less than or equal to"?

• $$<$$  

• $$=$$  

• $$\ge$$  

• $$\le$$  

Multiple Choice

What does this mean?

$$\ge$$  

• greater than

• greater than or equal to

• less than

• less than or equal to

Multiple Choice

What does this mean?

$$<$$  

• greater than

• less than

• greater than or equal to

• less than or equal to