Solve by Factoring y^2-y-72=0

$y^{2} - y - 72 = 0$

Step 1

Factor $y^{2} - y - 72$ using the AC method.

Consider the form $x^{2} + b x + c$ . Find a pair of integers whose product is $c$ and whose sum is $b$ . In this case, whose product is $- 72$ and whose sum is $- 1$ .

$- 9, 8$

Write the factored form using these integers.

$(y - 9) (y + 8) = 0$

Step 2

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$y - 9 = 0$

$y + 8 = 0$

Step 3

Set $y - 9$ equal to $0$ and solve for $y$ .

Set $y - 9$ equal to $0$ .

$y - 9 = 0$

Add $9$ to both sides of the equation.

$y = 9$

Step 4

Set $y + 8$ equal to $0$ and solve for $y$ .

Set $y + 8$ equal to $0$ .

$y + 8 = 0$

Subtract $8$ from both sides of the equation.

$y = - 8$

Step 5

The final solution is all the values that make $(y - 9) (y + 8) = 0$ true.

$y = 9, - 8$

Solve by Factoring y^2-y-72=0

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