Question

Solve the system by substitution.

Answer 1

Solving by substitution means that you take one of the equations and isolate for just one variable, then "substitute" it into the other.

Following so far?

Answer 2

You can pick either equation to isolate with(doesn't matter).

Your equations are:

2x + y = -11
and 3x -4y = 11

So I'll randomly choose the first one and isolate for y:
2x + y = -11

I'll subtract 2x from each side:
2x - 2x + y = -11 - 2x
y = -11 - 2x

Answer 3

Now I'll substitute that into the other equation:
( y = -11 - 2x into 3x - 4y = 11 )

3x - 4(-11 - 2x) = 11

Answer 4

If you distribute/multiply through:
3x - 4(-11 - 2x) = 11
3x + 44 + 8x = 11 <-- be careful with positive/negative signs here

Now you can solve for x.

You're not quite done yet but is this helping?

Answer 5

11x +44 =11

Answer 6

11x = 33

Answer 7

2

Answer 8

i wonder which the answer choice would be :(

Answer 9

so it's gotta be c or b!

Answer 10

you had a good start!

11x + 44 = 11

subtract 44 from both sides:
11x + 44 - 44 = 11 - 44

11x = -33 <-- be careful with negatives :)

divide both sides by 11:
(11x) / 11 = (-33)/11

x = -3

Answer 11

oh X = -3 so it's C

Answer 12

because in b y = -3 :)

Answer 13

Therefore it must be C.

But if you want to calculate y:

take x and substitute into either equation:
2x + y = -11
2(-3) + y = -11
-6 + y = -11

add 6 to both sides:
-6 +6 + y = -11 + 6
y = -5 :)

Answer 14

thank you so much @redshift you are so nice and smart

Answer 15

haha thanks :)