Question

СРОЧНО ДАМ 100 БАЛЛОВ 2;3;4 ХЕЕЛП

Answer 1

2.

$\left \{ {{5x-3y=7} \atop {7x-6y=9}} \right. \left \{ {{-3y=7-5x} \atop {7x-6y=9}} \right. \left \{ {{3y=5x-7} \atop {7x-6y=9}} \right. \left \{ {{6y=10x-14} \atop {7x-(10x-14)=9}} \right. \left \{ {{6y=10x-14} \atop {7x-10x+14=9}} \right. \left \{ {{6y=10x-14} \atop {-3x=9-14}} \right.$

$\left \{ {{6y=10x-14} \atop {-3x=-5}} \right. \left \{ {{3y=5x-7} \atop {x=\frac{5}{3}}} \right. \left \{ {{3y=5\cdot \frac{5}{3}-7} \atop {x=\frac{5}{3}}} \right. \left \{ {{3y= \frac{25}{3}-7} \atop {x=\frac{5}{3}}} \right.\left \{ {{3y= \frac{25-21}{3}} \atop {x=\frac{5}{3}}} \right.\left \{ {{3y= \frac{4}{3}} \atop {x=\frac{5}{3}}} \right. \left \{ {{y= \frac{4}{9}} \atop {x=\frac{5}{3}}} \right.$

3.

$\left \{ {{3\cdot (2x-y)-5\cdot (x+y)=-7} \atop {2\cdot (x+4y)-5y=5}} \right. \left \{ {{6x-3y-5x-5y=-7} \atop {2x+8y-5y=5}} \right. \left \{ {{x-8y=-7} \atop {2x+3y=5}} \right. \left \{ {{x=8y-7} \atop {2\cdot (8y-7)+3y=5}} \right. \left \{ {{x=8y-7} \atop {16y-14+3y=5}} \right.$

$\left \{ {{x=8y-7} \atop {19y=5+14}} \right. \left \{ {{x=8y-7} \atop {19y=19}} \right. \left \{ {{x=8\cdot 1 -7} \atop {y=1}} \right. \left \{ {{x=8-7} \atop {y=1}} \right. \left \{ {{x=1} \atop {y=1}} \right.$

4.

$\left \{ {{\frac{2x}{3}+\frac{7y}{2}=11} \atop {\frac{4x}{3}-\frac{y}{2}=7}} \right. \left \{ {{4x+21y=66} \atop {8x-3y=42}} \right. \left \{ {{8x+42y=132} \atop {8x-3y=42}} \right. \left \{ {{8x=132-42y} \atop {132-42y-3y=42}} \right. \left \{ {{8x=132-42y} \atop {-45y=42-132}} \right. \left \{ {{8x=132-42y} \atop {-45y=-90}} \right.$

$\left \{ {{4x=66-21y} \atop {y=2}} \right. \left \{ {{4x=66-21\cdot 2} \atop {y=2}} \right. \left \{ {{4x=66-42} \atop {y=2}} \right. \left \{ {{4x=24} \atop {y=2}} \right. \left \{ {{x=6} \atop {y=2}} \right.$

Answer 2

Решение приложено....