Question

solve (6-2x) × (6-2x) = 20

Answer 1

Hi ,

( 6 - 2x ) ( 6 - 2x ) = 20

( 6 - 2x )² = 20

6² - 2 × 6 × 2x + ( 2x )² = 20

36 - 24x + 4x² = 20

Divide each term with 4 , we get

9 - 6x + x² = 5

x² - 6x + 9 - 5 =0

x² - 6x + 4 = 0

Compare with ax² + bx + c = 0 we get

a = 1 , b = -6 , c = 4

D = b² - 4ac = ( -6 )² - 4 × 1 × 4

= 36 - 16

D = 20

x = ( -b ± √D ) / 2a

= [ -(-6 ) ± √20 ] / ( 2 × 1 )

= ( 6 ± 2√5 ) /2

= 3 ± √5

I hope this helps you.

:)