Question

Given that 2x²−kx+18 is a perfect square, find k and hence solve the equation 2x²−kx+18=0 by factorization. 

Answer 1

(−k)² = 2 × 18
( 2 )
     K² =36 × 4
         =144
       K=±12
2x² − 12x + 18 = 0
2x² − 4x − 9x + 18 = 0
2x(x−2) −9(x−2) = 0
(x−2) (2x−9) = 0
x = 2
x=4½