Question 60453
   9x-5x^2=-2
  5x^2-9x-2=0  taking all the terms to the rightside
5x^2-10x+x-2=0  by splitting the middle term so that sum is-9 product is-10
5x(x-2)+1(x-2)=0  taking common terms
(5x+1)(x-2)=0
x=-1/5 or x=2 is the answer.

ii)2x^2-3x=x^2+18
  2x^2-3x-x^2-18=0   x^2-3x-18=0
x^2-6x+3x-18=0  splitting the middle term so that sum is-3 and product is-18
x(x-6)+3(x-6)=0taking common terms
(x+3)(x-6)=0
x=-3 or x=6 is the answer.

iii)15x^2 +x=2   15x^2+x-2=0  taking all the terms to l.h.s.
15x^2 +6x-5x-2=0   3x(5x=2)-1(5x+2)=0  productis -2 and sum is1 
(3x-1)(5x+2)=0
x=1/3 or x=-2/5 is the answer.

iv)x^2-6x+9=16 taking all teh terms to l.h.s. we get
  x^2-6x+9-16=0   x^2-6x-7=0
  x^2-7x+x-7=0   product is -7 and sum is-6
  x(x-7)+1(x-7)=0 
  (x-7)(x+1)=0
   x=-1or x=7 is the answer.