Question

HELP ME PLEASE!!!!!
Solve, using the substitution method.

y – 3x = 7
21 + 9x = 3y

A.
There is no solution.

B.
There are an infinite number of solutions.

C.
The solution is (1, 10)

D.
The solution is (28, 0)

Answer 1

hint:

y – 3x = 7

y – 3x+3x = 7+3x

y + 0x = 3x + 7

y + 0 = 3x + 7

y = 3x + 7

Answer 2

Wait I Dont get the second part

Answer 3

21 + 9x = 3(3x+7)

Answer 4

do you see how I went from y – 3x = 7 to y = 3x + 7 ?

Answer 5

3(3x+7) distributes to 3*3x+3*7 and that turns into 9x + 21

Answer 6

yes

Answer 7

21 + 9x = 3(3x+7)

turns into

21 + 9x = 9x + 21

Answer 8

but what do you do when its 9x + 21=9x + 21

Answer 9

whats the soulution thats what im stuck on

Answer 10

what happens when you subtract 9x from both sides

Answer 11

21=21

Answer 12

is that always true? sometimes true? or always false?

Answer 13

idk

Answer 14

is 21 equal to itself?

Answer 15

yes

Answer 16

so this never changes, so it's always true

Answer 17

so is it a b c or d

Answer 18

because it's ALWAYS true, this means that x and y have no effect at all

Answer 19

so x can be any real number and the system would have a solution

Answer 20

so it b

Answer 21

There are an infinite number of solutions

Answer 22

Am i right?

Answer 23

yes you are

Answer 24

ok thanks alot

Answer 25

you're welcome

Answer 26

GUYS @jim_thompson5910 IS THE BEST!!!!!!!!!!