Question

i need some reviewing on elimination.
-4x - 2y = -12
4x + 8y = -24
prefer if steps can be shown and possibly explain.

Answer 1

elimination is when we add the two equations together and one of the variables goes away

Answer 2

if we add these 2 together, do you see a variable that goes away?

Answer 3

add both sides--> 6y=-36
y=-6
replace y=-6 in one of the eq--> 4x=-24+48
4x=24
x=6
solution (6;-6)

Answer 4

4x goes away

Answer 5

that right, the x part goes away leaving us with only the y part to solve for :)

Answer 6

well, i am a little stuck on the substituting part. why wouldn't it be 4x = -24 -48. because -6*8 is negative

Answer 7

add the two equations in a column.
\[-4x+4x=0\]

\[-2y+8y=6y\]

\[-12+-24=-36\]

Answer 8

now you have
\[6y=-36\] so
\[y=\frac{-36}{6}\]

\[y=-6\]

Answer 9

now y is not a mystery or a variable, it is known to be -6, so the first equation is
\[-4x-2(-6)=-12\]
and so
\[-4x+12=-12\] subtract 12 from both sides to get
\[-4x=-24\] divide by -4 to get
\[x=\frac{-24}{-4}=6\]

Answer 10

elimination is another way to solve for the system of equations; "substitution" in general is not needed as a result

Answer 11

but i see this is solved earlier, so not sure what i added if anything

Answer 12

you added blood sweat and tears :)

Answer 13

you are showing your age!

Answer 14

thanks for helping. i got it now. you cleared things up.