Question

resolva os sistemas pelo método da substituição:

a) {x-y=1
{x+y=9

b) {x+y=8
{x-y=2

c) {x-y=4
{2x-y=5

d){3x-y=7
{4x-5y=2

e) {x+3y=1
{5x+3y=17

f) {x-2y=7
{3x+y=35

g) {7x+y=42
{3x-y=8

h) {x+y=5
{4x-y=0

i) {x-2y=18
{x+4y=6

j) {x=y+2
{x+y=8

Answer 1

a) x=9-y
9-y-y=1
-2y=1-9
-2y=-8
y=-8/-2
y=4
x=9-4
x=5

b)x=8-y
8-y-y=2
-2y=2-8
y=-6/-2
y=3
x=8-3
x=5

c) x=4+y
2(4+y)-y=5
8+2y-y=5
2y-y=5-8
y=-3
x=4+3
x=7

d)-y=7-3x
y=-7+3x
4x-5 (-7+3x)=2
4x+35-15x=2
4x-15x=2-35
-11x=-33
x=-33/-11
x=3
y=-7+3×3
y=-7+9
y=2

e) x=1-3y
5 (1-3y)+3y=17
5-15y+3y=17
-15y+3y=17-5
-12y=12
y=12/-12
y=-1
x=1-3×-1
x=1+3
x=4

f) x=7+2y
3 (7+2y)+y=35
21+6y+y=35
+6y+y=35-21
7y=14
y=14/7
y=2
x=7+2×2
x=7+4
x=11

g)-y=8-3x
y=-8+3x
7x-8+3x=42
7x+3x=42+8
10x=50
x=50/10
x=5
y=-8+3×5
y=-8+15
y=7

h) x=5-y
4 (5-y)-y=0
20-4y=0
-4y=0-20
-4y=-20
y=-20/-4
y=5
x=5-5
x=0

i) x=18+2y
18+2y+4y=6
2y+4y=6-18
6y=-12
y=12/6
y=2
x=18+2×2
x=18+4
x=14

j) x=y+2
y+2+y=8
y+y=8-2
2y=6
y=6/2
y=3
x=3+2
x=5
espero ajudar ♥