Answer: a. x=3 or 5
Explanation:
x^2-8x+15=0
When factoring this equation we need to find 2 numbers that multiply to get positive (15) and add to get negative (-8)
So -3 and -5 fit this description because -3+-5=-8 and -3*-5=15
(x-3)(x-5)=0
Solve for values of x to get x=3 and x=5
so X=3 or 5