Question

Solve this system of equation using any method. 4x-y=5 and 3x+y=16

Answer 1

multiply 4x-y=5 by 3 (everything so it would be 12x -3y =15.
multiply 3x +y = 16 by 4 (12x- 4y = 64)
set it up like an elimination problem
12x -3y =15
-12x-4y =64
----------------
1x = -49
x= -49

plug x back into the original equation----->
4(-49) -y =5
-169 -y = 5
+169. +169
x = 174

Answer is (174, -49)



I think, check my work

Answer 2

Since one equation has a positive y and the other a negative value, the simplest way is to add together the two equation to cancel out y first...

(4x-y=5)+(3x+y=16)

7x=21 now divide both sides by 7

x=3, and use either original equation to solve for y...

3(3)+y=16

9+y=16

y=7

So the solution is the point (3,7)