Question

a.{3x+7y=-11
{-5x-8y=11
b.{10x-7y=-18
{-4x+5y=16
c.{2x+5y=0
{-x-4y=3
d.{5x+3y=-35
{15x-7y=-25
Coroana!!!

Answer 1

a. {3x+7y=-11 |*5
{-5x-8y=11 |*3 <=>
{15x+35y=-55
{-15x-24y=33

/ 11y=-22 => y=-2
3x+7*(-2)=-11
3x-14=-11
3x=3
x=1

b. {10x-7y=-18 |*5
{-4x+5y=16 |*7 <=>
{50x-35y=-90
{-28x+35y=112

22x / = 22 => x=1
10*1-7y=-18
-7y=-28
y=4

c. {2x+5y=0
{ -x-4y=3 |*2 <=>
{2x+5y=0
{-2x-8y=6

/ -3y=6
y= -2
2x+5y=0
2x+5*(-2)=0
2x-10=0
2x=10
X=5

d. {5x+3y=-35 |*(-3)
{15x-7y=-25 <=>
{-15x-9y=105
{15x-7y=-25

/ -16y=80
y=-5

5x+3*(-5)=-35
5x-15=-35
5x=-20
x=-4