10x^2+25x=20
2x^2+5x=4
2x^2+5x-4=0
x^2+5x/2-2=0
x^2+5x/2+25/16-25/16-2=0
(x+5/4)^2-57/16=0
(x+5/4-√57/4)(x+5/4+√57/4)=0
x=-5/4+√57/4或x=-5/4-√57/4若x的系数为35呢？帮忙再解一下，急！10x^2+35x=202x^2+7x=42x^2+7x-4=0(2x-1)(x+4)=0x=1/2或x=-4