Question 262455
I am trying to help my niece with her homework and I need step-by-step instructions on how to use substitution to solve a system of equations.
Example:
2x + 3y = 5
4x - 9y = 9
------
These are optional steps. There are many ways to
proceed.
----
1st: Solve the 1st equation for "x", as follows:
2x + 3y = 5
2x = -3y + 5
x = (-3y+5)/2
---------------------------
2nd: Substitute for "x" in the 2nd original equation and solve for "y":
4[(-3y+5)/2] - 9y = 9
2(-3y+5) - 9y = 9
-6y + 10 - 9y = 9
-15y = -1
y = 1/15
----------
Since x = (-3y+5)/2, x = (-3(1/15)+5)/2,
x = [(-1/5)+5/2 = (24/5)/2 = 12/5
------------------------
Final Answer: y = -1/3 when x = 12/5
=======================================
Cheers,
Stan H.