Answer:
Step-by-step explanation:
The given quadratic equation is expressed as
x^2 + 17x − 12 = −84
Adding -84 to the left hand side and the right hand side of the equation, it becomes
x^2 + 17x − 12 + 84 = −84 + 84.
x^2 + 17x + 72 = 0
We would find two numbers such that their sum or difference is 17x and their product is 72x^2. The two numbers are 8x and 9x. Therefore
x^2 + 8x + 9x + 72 = 0
x( x + 8) + 9(x + 8) = 0
x + 9 = 0 or x + 8 = 0
x - 9 or x = 8
