CPM Homework Help : ACC7 Problem 2-9

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2-9.

One meaning of the word evaluate is to find the value of an expression. To evaluate, replace a variable with a number and calculate the result. For example, when you are asked to evaluate the expression $4x-2$ when $x=-7$ , you would put $-7$ in place of the variable and calculate: $4·(-7)-2=-30$ .

Evaluate the expressions below for the given values of $x$ and $y$ .

Hint:

Rewrite the expression with the number in place of the variable and simplify if possible.

$\frac{6}{x}+9$ if $x=3$
Step 1 (a):
$\frac{ 6 }{(3) } + 9 =$
Hint (a):
Remember $\frac{6}{3}$ is the same as $6$ divided by $3$ .
Answer (a):
$11$

$8x-3+y$ if $x=2$ and $y=1$
Step 1 (b):
$8(2)-3+(1)$
Hint (b):
Try evaluating this one on your own.

$2xy$ if $x=5$ and $y=-3$
Step 1 (c):
$2(5)(-3)=10(-3)$
Answer (c):
$-30$

$2x^2-y$ if $x=3$ and $y=8$
Step 1 (d):
$2(3)^2-(8)$
Hint (d):
Try evaluating this one on your own. You have been given a head start.