Question

Please Help Me With This Problem, I Don't Quite Know How To Do It. . .
What Is The Solution Of The System? Use Substitution.
x=y-6
6x-3y=-9

Answer 1

replace x in the second equation by y - 3, and get an equation with y alone
\[6(y-3)-3y=-9\]

Answer 2

then solve for y. don't forget the distributive law.
\[6y-18-3y=-9\]
\[3y-18=-9\]
\[3y=9\]
\[y=3\]

Answer 3

I Got 6y-18-3y=9. . Now What Can I Do ?

Answer 4

Ohhh. Okay. Thank You Sooo Much!

Answer 5

oops i made a mistake. it was y- 6 not y - 3

Answer 6

i goofed.
\[6(y-6)-3y=-9\]

Answer 7

\[6y-36-3y=-9\]
\[3y-36=-9\]
\[3y=27\]
\[y=9\]

Answer 8

now since \[x=y-6\] and we know \[y=27\]
we get \[x=27-6=21\]

Answer 9

sorry about my typo

Answer 10

thank you, and no problem, thanks!♥

Answer 11

welcome

Answer 12

Wait. . But The Multiple Choice Says: A.(-2,-3) B.(-2-2.7) C.(-3,-2) D.(3,5) And 21 Isn't Either of those. . . .

Answer 13

let me check see if i made a mistake

Answer 14

Okay, And It Says To Eliminate, Not Substitute.

Answer 15

ok yes i made a mistake. i wrote \[y=9\] but then for some reason wrote \[x=27-6\] instead of \[x=9-6=3\]

Answer 16

my fault sorry. i do not know why i put y = 9 and then used y = 27 however, i am sticking with (3,9) and the check is easy:
first equation x= y - 6
and 3 = 9 - 6
second equation is \[6x-3y=-9\]
and \[6\times 3 - 3 \times 9 = 18-27=-9\]

Answer 17

so (3, 9) is right even if it is not one of the choices.

Answer 18

elimination:
rewrite \[x=y-6\]
as \[x-y=-6\]
and put \[6x-3y=-9\] underneath so it looks like
\[x-y=-6\]
\[6x-3y=-9\]

Answer 19

if you want to eliminate the "y" multiply the top equation all the way across by -3 to get
\[-3x+3y=18\]
\[6x-3y=-9\]

Answer 20

that way when you add the "y"s will drop out to give
\[3x=9\] and so \[x=3\]

Answer 21

dont forget to multiply EVERYTHING by the constant, otherwise you will not have the same equation.

Answer 22

now you know \[x=3\] you can substitute back to find y = 9. as before.

Answer 23

Thank You!! (=