SOLUTION: I understand how to do these but for sme reason this one is giving me a problem could you please help? Use sustitution to solve: 2x+y=7 5x-2y=4 tha

Algebra ->  Graphs -> SOLUTION: I understand how to do these but for sme reason this one is giving me a problem could you please help? Use sustitution to solve: 2x+y=7 5x-2y=4 tha      Log On


   

Question 24435: I understand how to do these but for sme reason this one is giving me a problem could you please help?
Use sustitution to solve: 2x+y=7
5x-2y=4
thank you
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solve by substitution:
1) 2x%2By+=+7 Write this in terms of y:
1a)y+=+-2x%2B7 and substitute into equation 2) then solve for x.
2) 5x-2y+=+4
5x-2%28-2x%2B7%29+=+4 Simplify and solve for x.
5x%2B4x-14+=+4
9x-14+=+4 Add 14 to both sides of the equation.
9x+=+18 Divide both sides by 9.
x+=+2 Now substitute this value of x into equation 1a) and solve for y.
y+=+-2x%2B7
y+=+-2%282%29%2B7
y+=+-4%2B7
y+=+3
The solution is: (2, 3)
Here's the graphical solution: Red line is:y+=+-2x%2B7 Green line is:y+=+%285%2F2%29x-2
graph%28300%2C200%2C-5%2C5%2C-5%2C8%2C-2x%2B7%2C%285%2F2%29x-2%29