Question

QUESTION FOR 50 POINTS
Solve this equation using an algebraic method: (x + 4)(x - 4) = 9
Choices are:
x=5
x=4 and x=-4
x=9
x=5 and x=-5

Answer 1

(x+4)(x-4)=9  expand left side by performing indicated multiplication...

x^2-16=9 add 16 to both sides

x^2=25  take the square root of both sides...

x=±5

x=-5 and 5

So the answer would be the bottom choice.

Answer 2

the answer is 
x=5 and x=-5