Question 97573: How do you solve this equation??
5x-y=10
7x-2y=11
Answer by Msgenes(10)   (Show Source):
You can put this solution on YOUR website! There are two ways of doing this problem by elimination or substitution. I am doing the substitution. Either way you do it you will get the same answer.
5x - y = 10
7x - 2y = 11
We want to get y by itself using the first equation, we do this by substracting 5x on both sides.
5x - y - 5x = -5x + 10
-y = -5x + 10
Now we know that y cannot be negative so we divid by -1 on both sides.
-y/-1 = -5x/-1 + 10/-1
y = 5x - 10
Now we are ready to substitute.
7x - 2y = 11
7x - 2(5x - 10) = 11
7x - 10x + 20 = 11
-3x + 20 = 11
-3x + 20 - 20 = 11 - 20
-3x = -9
Now we know that x cannot be negative so we divid by -3 on both sides
-3x/-3 = -9/-3
x = 3
Now we have to find y by substituting x for 3.
y = 5x - 10
y = 5(3)- 10
y = 15 - 10
y = 5
The solution is (3, 5)
To Check this we just plug the solution into the equation.
7x - 2y =11
7(3) - 2(5) = 11
21 - 10 = 11
11 = 11
Good Luck. Hope this helps. :)
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