X²+x-90=0 using completing the square method

x = - 10, x = 9

Step-by-step explanation:

Given

x² + x - 90 = 0 ( add 90 to both sides )

x² + x = 90

To complete the square

add ( half the coefficient of the x- term )² to both sides

x² + 2( )x + = 90 +

(x + )² = ( take the square root of both sides )

x + = ± = ± ( subtract from both sides )

x = - ± , thus

x = - - = = - 10

x = - + = = 9

i used to know how to do this in 7th but i forget easily

step-by-step explanation: