Question

Im clueless on these questions!!! PLEASE HELP!!!

(1) Solve by Substitution: 2x + y = 0
x – 3y = -7

(2) Solve by Elimination: 3x + 4y = 1
5x – 3y = 21

Answer 1

I will fan and give medal!!!

Answer 2

Alright. I will io step by step. Ok?

Answer 3

go*

Answer 4

ok.

Answer 5

make one a y=mx+b equation and put in place of the other equations y

Answer 6

(1) Solve by Substitution: 2x + y = 0
x – 3y = -7
you want one equation to equal either x or y

Answer 7

ok

Answer 8

so out of:
2x + y = 0
x – 3y = -7

it would be easier to get x by itself in the second question

x – 3y = -7
add 3y to both sides

x= 3y -7

Answer 9

simple make one a y= m x + b equation and put into the place of the other equations y

Answer 10

ok @WinterRaine ... i'm following.

Answer 11

so you substitute
x= 3y -7
into the other equation

2x + y = 0
2(3y -7) +y =0

Answer 12

in the 2nd equation, wouldn't it be 2(3y -7) + x =0 ?? instead of y?

Answer 13

your two equations look like this:

x – 3y = -7 (x= 3y -7)
&
2x + y = 0

Answer 14

Yes, I understand that.

Answer 15

so when you substitute x – 3y = -7 into the other equation, you just put it where the x is

so
2(3y -7) +y =0

Answer 16

ohhhhhh ok! please continue (:

Answer 17

alright so you solve the equation for y

2(3y -7) +y =0
distribute
6y - 14 + y=0
combine like terms
7y -14 =0
get the y by itself (add 14 to both sides)
7y = 14
divide by 7 on both sides
y =2

Answer 18

ok. now we have to solve for x now right?

Answer 19

yeah. so substitute y=2 into x= 3y -7

Answer 20

x = -1

Answer 21

yes!

Answer 22

((((((((:

Answer 23

Thank you soooo much. Mind doing the other one with me?

Answer 24

sure!

Answer 25

(2) Solve by Elimination: 3x + 4y = 1
5x – 3y = 21

Answer 26

we'll use this equation to start off:

3x + 4y = 1
we'll get x by itself for this one

subtract 4y from both sides
3x = -4y +1

Answer 27

3x = -4y +1
divide by 3 on both sides

x = -4/3x + 1/3

Answer 28

ok.

Answer 29

so put x = -4/3y + 1/3 into

5x – 3y = 21

5(-4/3y + 1/3) -3y =21

Answer 30

-6 2/3y + 5/3 - 3y= 21

Answer 31

ok...

Answer 32

OR
-20/3y + 5/3 -3y= 21

combine like terms
-29/3y + 5/3 = 21

get y by itself (subtract 5/3)
-29/3y = 19.34

Answer 33

I'm sorry-- I have to go. @Easyaspi314 should be able to help you along and explain it better than I have (:

Answer 34

Good luck & I hope you understand substitution better!

Answer 35

ok thanks. @WinterRaine ... @RosieS12 could you finish where he left off?

Answer 36

so which part did u not understand?