1). x^2-8x-20= -15-x+x^2; x^2-8x+x-x^2= -15+20; -7x=5; x= -5/7. 2).47-11x+x^2=19x+x^2; -11x+x^2-19x-x^2= -47; -30x= -47; x=(-47)/(-30)= 1 17/30. 3). 33x-x^2=35x-x^2-17; 33x-x^2-35x+x^2= -17; -2x= -17; x=(-17)/(-2)=8,5. 4). 59x+4x^2= -4x+4x^2+21; 4x^2+4x-4x^2+59x=21; 63x=21; x=21/63=1/3.