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3 years ago

Use completing the square to solve for x in the equation (x-12)(x+4)=9

Mathematics

2 answers:

andreyandreev [35.5K]3 years ago

4 0

Answer:

Step-by-step explanation:

lets foil it and complete the square

x^2+4x-12x-48=9

x^2-8x=57

(-8/.5)^2=16

(x-4)^2-73

bogdanovich [222]3 years ago

3 0

Answer:

Choice d is the answer.

Step-by-step explanation:

We have given a equation.

(x-12)(x+4) = 9

We have to find the solution using completing square technique.

Simplifying given given equation, we have

x²+4x-12x-48 = 9

Adding 48 to both sides of above equation, we have

x²-8x-48+48 = 9+48

x²-8x = 57

Adding the square of half of the term -8x to both sides of above equation, we have

x²-8x+(-4)² = 57+(-4)²

x²+2(1)(-4)+(-4)² = 57+16

(x-4)² = 73

Taking square root to both sides of above equation, we have

√(x-4)² = √73

x-4 = ±√73

Adding 4 to both sides of above equation, we have

x-4+4 = ±√73+4

x = 4±√73 which is the answer.

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