Question

solve the following quadratic equations by completing the square method. x square +x-20=0

Answer 1

Hi ,

x² + x - 20 = 0

x² + x = 20

x² + 2 × x × ( 1/2 ) = 20

x² + 2 × x × ( 1/2 ) + ( 1/2 )² = 20 +( 1/2 )²

( x + 1/2 )² = 20 + 1/4

( x + 1/2 )² = ( 80 + 1 )/4

( x + 1/2 )² = 81/4

x + 1/2 = ± √ ( 81/4 )

x + 1/2 = ± 9/2

x = -1/2 ± 9/2

Therefore ,

Required roots are ,

x = - 1/2 + 9/2 = 8/2 = 4

Or

x = -1/2 - 9/2 = -10/2 = -5

I hope this helps you.

: )

Answer 2

hope it helps...
it's the answer