Question 967531: whats x and y for 4x+3y=-10 and 9x+2y=6?
Answer by ikleyn(52782)   (Show Source):
You can put this solution on YOUR website!
You need to solve the system of two linear equations in 2 unknowns
Multiply the first equation by 2 and the second equation by -3. Then add the obtained equations. You will get
8x + 6y = -20,
+
-27x - 6y = -18
-------------
-19x = -20 - 18 = -38.
Hence, x =  =  = 2.
Now, substitute the found value of x = 2 into the either equation of your original system, for example, into the first equation. You will get
4*2 + 3*y = -10, or
8 + 3*y = -10, or
3y = -10 - 8 = -18.
Hence, y =  = -6.
Answer. The solution of the system is x = 2, y = -6.
We applied here the Elimination method.
For solving systems of two linear equations in three unknowns see the lessons
- Solution of the linear system of two equations in two unknowns by the Substitution method,
- Solution of the linear system of two equations in two unknowns by the Elimination method,
- Solution of the linear system of two equations in two unknowns using determinant,
- Geometry interpretation of the linear system of two equations in two unknowns and
- Solving word problems using linear systems of two equations in two unknowns.
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