3) 4a²(x+7)+3(x+7)=4a²x+28a²+3x+21
a=-0.5 x=1.05
4×0,25×1,05+28×0,25+3×1,05+21=1,05+7+3,15+21=32,2
5)1.(x-5)(x-2)-(x+1)(x-4)=6
x-5×x-2-x+1×x-4=6
x-5x-2-x+1x-4=6
-4x-6=6
-4x=6+6
-4x=12
x=12÷(-4)
x=-3
1.в)-4y×2x³-3x×5y+2x³y+7,5x×2y=-8x³y-14xy+2x³y+15xy=-6x³y+1xy