Question

Solve using perfect square factoring patterns. x2 – 10x + 25 = 9 A. {4, –12} B. {2, 8} C. {–8, –2} D. {–4, 12}

Answer 1

x² - 10x + 25 = 9 
x² - 10x +16 = 0  <---- subtracted 9 from each side .....
Since you there are no factors of 16 that add up to -10 do the quadratic formula : -b + √b² - 4ac 
             -------------------------
                        2a 

-(-10) + √(10)² - 4(1)(16) 
10 + √36 
10 + 6 
10 + 6 = 16
16 / 2 = 8 <--- your first answer 

10 - 6 = 4
4 / 2 = 2  <---- your other answer

so your answer is B { 2,8 }