Question 499027
b(b+9)=4(5+2b)
b^2 + 9b = 20 + 8b
b^2 +9b - 8b - 20 = 0
b^2 + b - 20 = 0
1^2 - 4*1*-20 = 81
(-1 +/- 9)/2
x'= -5
x" = 4