Question Find the values of $a$ that satisfy the equation $-9a + 9 = -72$ .

Studdy Solution

STEP 1

Assumptions
1. The equation is $-9a + 9 = -72$
2. The possible solutions given are $a = -7$ and $a = 9$

STEP 2

First, we will substitute $a = -7$ into the equation to check if it is a solution.
$-9a + 9 = -72$ $-9(-7) + 9 = -72$

STEP 3

Calculate the left side of the equation.
$63 + 9 = -72$

STEP 4

Calculate the sum on the left side of the equation.
$72 = -72$

STEP 5

We can see that the left side of the equation is not equal to the right side, so $a = -7$ is not a solution to the equation.

STEP 6

Next, we will substitute $a = 9$ into the equation to check if it is a solution.
$-9a + 9 = -72$ $-9(9) + 9 = -72$

STEP 7

Calculate the left side of the equation.
$-81 + 9 = -72$

STEP 8

Calculate the sum on the left side of the equation.
$-72 = -72$

STEP 9

We can see that the left side of the equation is equal to the right side, so $a = 9$ is a solution to the equation.
The value of $a$ that is a solution to the equation is $a = 9$ .

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