3.5a²b³a³b⁴c*(-2/7)abc³ = 3.5 * (-2/7) * a²a³a * b³b⁴b * cc³ =<span>-a⁶b⁸c⁴
</span>1) 3.5x³ - 2.5x³ = 0.5x³(7 - 5) = 0.5x³ * 2 = x³
2) 1/7ab + 2/3ab = ab(1/7 + 2/3) = ab(3/21 + 14/21) = ab * 17/21 = (17/21)ab
8(x+y)-12y=6,
6(3x-y)+18x=13;
8x+8y-12y=6,
18x-6y+18x=13;
8x-4y=6, |:2
36x-6y=13;
4x-2y=3, |*(-3)
36x-6y=13;
-12x+6y=-9,
36x-6y=13;
Сложим уравнения:
-12х+6у+36х-6у=-9+13,
2у=4х-3;
24х=4,
у=(4х-3)/2;
х=1/6,
у=-1 1/6;
Ответ: (1/6; -1 1/6)
-90+0.7(-10^3)
-90-0.7×1000
-90-700
-790