Решите систему уровнений групировки 9x+2y=3 5x-7y=9 x-3y=10 6x+5y=-16

9x+2y=3
x-3y=10/*(-9)⇒-9x+27y=-90
29y=-87
y=-3
x=10+3*(-3)=10-9=1
(1;-3)

5x-7y=9/*5⇒25x-35y=45
6x+5y=-16/*7⇒42x+35y=-112
67x=-67
x=-1
-6+5y=-16
5y=6-16=-10
y=-2
(-1;-2)

  \left \{ {{3x-8y=22} \atop {7x+8y=78}} \right.  \\ 3x+7x-8y+8y=22+78 \\ 10x=100 \\ x=10 \\ 3*10-8y=22 \\ 8y=30-22 \\ 8y=8 \\ y=1 \\ (10;1)2) \left \{ {{5x+7y=26} \atop {6x-7y=62}} \right.  \\ 5x+6x+7y-7y=26+62 \\ 11x=88 \\ x=8 \\ 5*8+7y=26 \\ 7y=-14 \\ y=-2 \\ (8;-2)3) \left \{ {{5x+2y=16} \atop {-5x-2y=20}} \right.  \\ 5x-5x+2y-2y=16+20 \\ 0 \neq 36 \\  \varnothing4) \left \{ {{9x-5y=23} \atop {9x+2y=-5}} \right.  \\ 9x-9x-5y-2y=23+5 \\ -7y=28 \\ y=-4 \\ 9x+20=23 \\ 9x=3 \\ x= \frac{1}{3}  \\ (\frac{1}{3};-4)
1) \left \{ {{5x+3y=63|*3} \atop {15x-8y=2}} \right.  \\ \left \{ {{15x+9y=189} \atop {15x-8y=2}} \right.  \\ 15x-15x+9y+8y=189-2 \\ 17y=187 \\ y=11 \\ 5x+3*11=63 \\ 5x=63-33 \\ 5x=30 \\ x=6 \\ (6;11)2) \left \{ {{3a+5b=51|*4} \atop {12a-11b=18}} \right.  \\ \left \{ {{12a+20b=204} \atop {12a-11b=18}} \right. \\ 12a-12a+20b+11b=204-18 \\ 31b=186 \\ b=6 \\ 3a+5*6=51 \\ 3a=51-30 \\ 3a=21 \\ a=7 \\ (7;6)3) \left \{ {{4c-3d=7|*2} \atop {5c+2d=26|*3}} \right.  \\ \left \{ {{8c-6d=14} \atop {15c+6d=78}} \right.  \\ 8c+15c-6c+6c=14+78 \\ 23c=92 \\ c=4 \\ 4*4-3d=7 \\ 3d=16-7 \\ 3d=9 \\ d=3 \\ (4;3)
вроде правильно :D