<PRE><B>Question 654294</B>
Hi. My problem is: Solve the linear system by using elimination 
So
7x - 4y = -30
3x + 4y = 10

I tried                    


7x -                        3•-2 
3x.                          -6 + 4y = 10
10x = -20 = (-2,  ).   +6.           +6
                                       4y = 16 / 4 = 4 ??? Am I performing this correct? Please help. Final answer is (-2,4)


7x - 4y = -30 (eq1)

3x + 4y = 10 (eq2)


7x - 4y + 3x + 4y = -30 + 10

Combine like terms:

7x + 3x = 10x

-4y + 4y = 0

-30 + 10 = -20

Therefore:

10x = -20

Divide each side by 10

10x/10 = -20/10

x = -2


3x + 4y = 10 (eq2)

3(-2) + 4y = 10

-6 + 4y = 10

Add 6 to each side of the equation.

-6 + 4y + 6 = 10 + 6

Combine like terms:

-6 + 6 = 0

10 + 6 = 16

4y = 16

Divide each side by 4

4y/4 = 16/4

y = 4


Check:

7x - 4y = -30

7(-2) - 4(4) = -30

-14 - 16 = -30


Therefore:
The Answer:

x = -2 and y = 4




Lennox Obuong
Algebra Student
Email: obuong3@aol.com</PRE>