Evaluating Variable Expressions

Order of operations

1

What does "PEMDAS" stand for?

P = parentheses E = exponents M = multiplication D = division A = addition S = subtraction

2

What does 8² mean?

8 times itself, or 8*8, or 64.

3

In the expression 6(7 + 9), which step should we start with according to PEMDAS?

7+ 9 = 16

4

Solve: 5(4² + 3)

 95

5

Solve: 7+6((6² + 5)-15)

163

Two-variable expressions

1

3(y + x) ; use x = 4, y = 0

3(4) = 12

2

4 + xy ; use x = 7 and y = 3

4 + 21 = 25

3

8(5 - x) - y ; use x = 3 and y = 12

8(5 - 3) - 12 = 8(2) - 12 = 16 - 12 = 4

4

(c + d) + 4(c) ; use c = 8, d = 9

(8 + 9) - 4(8) = 17 + 32 = 49

5

5(f - h) - 2h ; use h = –1, f = 2

5(2 - -1) - 2(-1) = 5(2 + 1) + 2 = 5(3) + 2 = 17

Expressions with Exponents

1

3x²-17 ; x=5

58

2

9²-x³ ; x=4

17

3

(74-t²)²÷s³(3t+1) ; s=1 & t=8

4

4

120÷(6²+t(2^t)) ; t=3

2

5

[7³(3p-9q)-5]÷q^p; p=7, q=2

8

Exponents

1

What is 2²?

4

2

What is 3³?

27

3

What is 1⁴?

1

4

What is 5³-4²?

109

5

What is 9⁴? 

6561

One-variable expressions

1

4(x) ; x = 12

48

2

3y ; use y =3

9

3

t÷18 ; t = 0

0

4

(5y - y)÷2 ; y = 6

(30 - 6)/2 = 24/2 = 12

5

(50 + g)÷g ; g = 10

6