How do you solve the quadratic #(x-5)(x+8)=-20# using any method?
1 Answer
Aug 16, 2016
Explanation:
#-20 = (x-5)(x+8)=x^2+3x-40#
Add
#0 = x^2+3x-20#
Multiply by
#0 = 4x^2+12x-80#
#=(2x)^2+2(3)(2x)+3^2-89#
#=(2x+3)^2-(sqrt(89))^2#
#=(2x+3-sqrt(89))(2x+3+sqrt(89))#
Hence
