<span>1.5х-9у-(у+1.5у)=5x -11.5y = 5*0.781 - 11.5*0.9= -6.445</span>
1) a(2a+b)(a+b) - 4a(a+b)^2 = a*(a+b)*(2a+b-4(a+b)) = a*(a+b)*(2a+b-4a-4b) =
= a*(a+b)*(-2a-3b);
2) 3m^2(m-8) + 6m(m-8)^2 = 3m*(m-8)*(m+2(m-8)) = 3m*(m-8)*(m+2m-16) =
= 3m * (m-8) * (3m-16);
3) (2a+3)(a+5) + (a-1)(a+5) = (a+5) * (2a+3+a-1) = (a+5)*(3a+2).
1) 4+1 =5 частей - всего
2) 100 : 5 = 20% - 1 часть
3) 4 х20 = 80% - хвойные деревья
4) 1 х 20 = 20% лиственные деревья
<span>(4 х+1)</span>²<span>-(4х+3)(4х-3) = 6x-2
16x</span>²+8x+1-(16x²-9)=5x-2
16x²+8x+1-16x²+9=6x-2
8x+10=6x-2
8x-6x=-2-10
2x=-12
x=-12:2
x=-6