1) 16x^2+49+56x-40x+1=15x^2+27x+50
x^2-11x=0
x=0 x=11
2) 9x^2-25=x^2-25-16x
8x^2+16x=0
x^2+2x=0
x=0 x= -2
3) 9+3x-6x-2x^2=(18-x^2)/2
18+6x-12x-4x^2=18-x^2
-5x^2-6x=0
x=0 5x+6=0
x=-6/5
4) 5x^2-10x+2x-4-x^2+1=4x-3
4x^2-8x-3=4x-3
4x&2-12x=0
x^2-3x=0
x=0 x=3