Question

Solve using Elimination.

7x + 8y =19
3x +9y = (-3)

Answer 1

are you solving for x or y?

Answer 2

Both.

Answer 3

x=-8y/7+19/7
y=-7x/8+19/8

Answer 4

that might be wrong bcuz i got all confused but thats what i got

Answer 5

Okay. Thanx

Answer 6

You can solve for x or y first--either way, you get the same answer at the end.
Using the first equation, we can solve for y in terms of x:
\[7x + 8y = 19\]
\[8y = 19-7x\]
\[y = \frac{19-7x}{8}\]
Now that we have y in terms of x, we can plug into the second equation to eliminate y and solve for a value of x:
\[3x + 9y = -3\]
\[3x + 9 \left( \frac{19-7x}{8} \right) = -3\]
Multiply by 8 on both sides or find the LCD to combine the fractions. I'll multiply by 8 here.
\[8 \times \left( 3x + 9 \left( \frac{19-7x}{8} \right) \right) = 8 \times -3\]
When we distribute, we can remove the 8 from the denominator so that we don't have to deal with fractions. Remember to multiply both sides of the equation, though!
\[24x + 9 \left( 19-7x \right) = -24\]
Distribute the 9
\[24x + 171 - 63x = -24\]
You should now be able to solve for x by combining like terms.

Now that we know what x is, we can plug back into the expression we solved for in the beginning that gives us what y is in terms of x:
\[y = \frac{19-7x}{8}\]
Then we will have solved for x and y.

Answer 7

Thnx for the explanation too