Question

Show that x=-3 is a solution of 2x square + 5x -3 =0

Answer 1

2x^2+5x-3=0

2x^2+6x-x-3=0

2x(x+3) -1(x+3) =0

(2x-1) (x+3) =0

therefore either

x+3=0 or

2x-1=0

so x=1/2 and x=-3

x=-3

hence proved