Noelle used the quadratic formula to solve x^2+10x+16=0. Delilah solved it without the quadratic formula. What did Delilah notice that enabled her to solve this equation without using the quadratic formula?
Delilah noticed that 16 could be expressed as 2*8 and that 10 could be expressed as 2 + 8.
Therefore, the equation can be written as (x + 2)(x + 8) = 0
Hence x = -2 and x = -8