Question

X2 +x-20=0 solve the following quadratic equation by completing square method

Answer 1

x^2+x-20=0

x^2+(5-4)x-20=0

x^2+5x-4x-20=0

x(x+5)-4(x+5)=0

(x-4)(x+5)=0

x-4=0         or             x+5=0

x=4             or            x=-5

Answer 2

x
${x }^{2} + ( 5 - 4)x - 20 = 0 \\ {x}^{2} + 5x - 4x - 20 \\ x(x + 5) - 4(x + 5) \\ = (x - 4)(x + 5)$
x=4 or x=-5