Question

Literal Equation: Help solve

3x-4y = 26
x - 8y = 22

Answer 1

3x-4y = 26 (-2)
x - 8y = 22

-6x+8y = -52
x - 8y = 22
-------------
-5x = -30


x = 6

Answer 2

x=6,y=-2

Answer 3

Why do you only subtract -2?

Answer 4

he is multiplying the whole equation with -2

Answer 5

you mulltiply the whole thing by (-2) in order to get an equation that can eliminate a variable

Answer 6

And you are elimination the Y?

Answer 7

yes; with the y gone, we can easily solve for x

Answer 8

What about substitution?

Answer 9

for example:

3x = 12; x=4

what happens if we multiply the whole thing by 5, does the x value change?

3x = 12 (5)

15x = 60 ; x = 4

Answer 10

substitution is just solving for one variable in the terms of the other ... its more labor intensive

Answer 11

subbing, elimiation, matrix .... all get the same answer so you eventually just go with whats best for you :)

Answer 12

Except rumor has it that this problem will be on a test with subbing instead!

Answer 13

How do you get to kentucky? lol

Answer 14

then solve for one variable in terms of the other; use that 'value' in the other eqaution to get a solid value for the 'other' variable; and use the solid value to determine the value of the unknowned

Answer 15

What if i took

3x - 4y = 26
x - 8y = 22 and i did this x = 22 + 8y

would that work?

Answer 16

that would work out great :)

Answer 17

since x=x=x=x=x... use that 'value' for x in the top and solve it all for y

Answer 18

Are you saying 3(22 + 8y) - 4y = 26
66 + 24y - 4y = 26

Answer 19

thats correct

Answer 20

Why do I flip it the 2nd equation though?

Answer 21

becasue you cant really determine the value of y from the first equation; you need another 'form' to use it in to calibrate the value

Answer 22

umm.... what do you mean by flip it?

Answer 23

Changing it from x - 8y = 22 to x = 22 + 8y

Answer 24

think of subbing as 'looking at it from another direction'...

Answer 25

x + y = 6 can have any values; and you cant determine x or y to be one point ..... so look at it thru a different equation right?

Answer 26

So in the

x - y = 4
4y - x = 14

could I change the x - y = 4 to x = 4 + y?

Answer 27

yes..... then we use that 'value' in the other equation to see it from a different perspective and can solve for y in it

Answer 28

or in the equation

x + y = 10
6x - 7y = 34

I can change the x + y = 10 to x = 10 - y?

Answer 29

exactly

Answer 30

I think I get it. If I don't I'll just ask you again :D

Answer 31

good idea ;)