SOLUTION: I have to do some problems like these two. Can anyone help me threw the steps on both of these so that I know how to do them. example 1 Solve the system. x + y = 9 x � y

Question 29018: I have to do some problems like these two. Can anyone help me threw the steps on both of these so that I know how to do them.
example 1
Solve the system.
x + y = 9
x � y = 3

Example 2
Solve the system by addition.
�4x + 5y = 1
x � 4y = 19

Answer by wuwei96815(245) (Show Source): You can put this solution on YOUR website!
These types of problems are best solve using elimination and substitution.

In the elimination part we have to eliminate one of the varibles so that we can solve for the other. When we add x+y=9 and x-y=3, we get 2x =12. What happened to the y's? They were eliminated (y-y=0). Now you can easily solve for x.
2x = 12
x = 6

Since we have the value of one of the variables, we can use substituion to find the other.
x+y=9
(6)+ y = 9
y=9+6 = 15

The second problem is more difficult because simply adding the equations together will not eliminate either variable. In the second problem try multiplying the second equation by 4 and then proceeding. Let me know how you make out.
RELATED QUESTIONS
Factor and check by multiplying x^8 + 3x^7 just Factor: 81c^6 - 3d^6 Are... (answered by richwmiller)

To be honest I am not sure what category it is. Can you please help me, I only know the... (answered by checkley71)

hello everyone. I have these two problems to solve about Relations and Functions so I... (answered by richard1234)

I have some algebra problems that i dont know how to do... Can you help... (answered by Edwin McCravy)

Hello, I would like to know, if possible can you please explain to me how these algebra... (answered by stanbon,nerdybill)

I have been studying all day and doing practice problems from my math book to get me... (answered by Jeef Gorrdon,richwmiller)

Hey guys! Almost out of Alg. II now (thank god)... Have a final coming up soon and I have (answered by askmemath,unreal)

How do I solve these two logarithms. I have the problems 5 ^x-1/3 = power 3 square (answered by josgarithmetic,MathTherapy)

I'm really having trouble with these few problems here and I can't call anyone from my... (answered by Earlsdon)