Find two numbers whose sum is 42 and whose difference is 16.

Question

chriss · Answer

x+y=42
x-y=16

anonymous · Answer

So Wats The answer?

chriss · Answer

You have to solve this system of equations to get the answer.  One way you could go about that would be to add the systems together.  This will eliminate the y and turn it into a single variable algebra problem.

x+y=42
x-y=16
-------
2x  = 58

Once you solve that for x, you can plug that result back in to either of the first two equations and solve for y.

anonymous · Answer

would the answer be 13 and 29??

chriss · Answer

That is correct :)

anonymous · Answer

Thanx alot ;p

chriss · Answer

you're welcome

anonymous · Answer

Hey Can u help me in this problem?

anonymous · Answer

Solve the system for the x-coordinate of the point of intersection.

3x + y = -2

2x - 5y = 4

chriss · Answer

This one you will want to use a similar method to the one above.  You want to eliminate the y.  The difference here is that just adding or subtracting won't be enough to do that for you.  The trick that you can use to do that though is to first multiply the first equation by 5, then your y-terms will be opposites and when you add the equations together, they will cancel each other out.

15x+5y=-10
  2x-5y=4
------------
17x    = -6

$$x=-\frac{6}{17}$$