Question

2x-y=8
7x-3y=27
Using the method of substitution solve these equations.
Write an ordered pair.

Answer 1

Solve the first equation for y

2x-y=8

-y=-2x+8

y = 2x-8

Then plug this into the second equation

7x-3y = 27

7x-3(2x-8) = 27

Keep going to solve for x

Answer 2

Once you have the solution for x, use this to find the solution for y.

Answer 3

Do you mind helping me with the steps?

Answer 4

Sure, the next step is to distribute

7x-3(2x-8) = 27

7x-3(2x)-3(-8) = 27

7x-6x+24 = 27

Then combine like terms

x + 24 = 27

What's next?

Answer 5

take 24 away from both sides?

Answer 6

good

Answer 7

giving you what

Answer 8

x=3

Answer 9

now use that to find y

Answer 10

plug it into y = 2x - 8

Answer 11

y=2(3)-8
y=6-8
y=2 ( I don't think I did that right)....?
that's my best guess

Answer 12

close

Answer 13

but 6 - 8 is negative since you're taking a larger number from 6

so 6 - 8 = -2

Answer 14

making y = -2

Answer 15

darn, i forgot about the sign....

Answer 16

think of it in terms of money

Answer 17

so the ordered pairs are (3, -2) yes?

Answer 18

you have $6 and you spend $8

you'll be in debt $2 or have -$2 on the balance sheet

Answer 19

exactly, x = 3 and y = -2 giving you (3,-2) as the solution

Answer 20

2x-y=8
7x-3y=27

1. take one of these equations
2. bring "x" on one side of equation and rest on other side (so u eliminated x from the other side)
3. put this x = .... any thing in the other equation (substitute that thing on the other side instead of x in the equation) u get an equation in y only
4. solve the equation in y only u get value of y
5. put this value of y in the other equation and solve u got the value of x

Answer 21

oooh, good idea. Thanks Jim!

Answer 22

yw