Question

please help
Use the Substitution Method to solve the following system of equations.
2x + y = 3
-3x + 4y = 1

(1, 1)

(-1, -1)

(1, -1)

(-1, 1)

Answer 1

solve the first equation for y

2x + y = 3

y = 3 - 2x

then plug this into the second equation

-3x + 4y = 1

-3x + 4(3 - 2x) = 1 .. replace y with 3-2x

-3x + 12 - 8x = 1

solve for x, then use this to solve for y

Answer 2

so x=1?

Answer 3

good

Answer 4

now plug that back into y = 3 - 2x to find y

Answer 5

y=3+2x?

Answer 6

y = 3 - 2x

Answer 7

it's minus, not plus

Answer 8

so the answer is? (1,1)

Answer 9

perfect

Answer 10

thank you!

Answer 11

you're welcome

Answer 12

what about this one?
What is the value of the x variable in the solution to the following system of equations?
2x + 3y = 4
x - 2y = -5

2

-2

1

-1

Answer 13

first solve for x in x - 2y = -5 to get

x - 2y = -5

x = -5+2y


now plug this into the first equation


2x + 3y = 4

2(-5+2y) + 3y = 4

-10+4y + 3y = 4

solve for y, then use this to solve for x

Answer 14

y=2

Answer 15

good, then use that to find x

Answer 16

how do I do that?

Answer 17

well remember we isolated x and got x = -5+2y

Answer 18

so if y = 2, then

x = -5+2y

x = -5+2*2 ... replace y with 2 (since y = 2)

x = -5 + 4

x = -1

Answer 19

thank you :)

Answer 20

you're welcome, keep practicing this and you'll definitely be a pro in no time

Answer 21

alright I will!