You have to decide which variable to eliminate.
Lets choose x. We need the coefficients to be equal and opposite. I will multiply the first equation by 3 and the second equation by -5
15x + 12y =42
-15x -30y = -30
Add the two equations and the x will be eliminated.
-18y = 12 y = -12/18 = -2/3
To find x - replace y with the answer. I will choose the second equation because it seems easier.
3x + 6(-2/3) = 6
3x -4 = 6
3x = 10
x = 10/3
(10/3, -2/3)
Check in both equation to be sure that a mistake hasn't been made.
Consider the following system of equations. Solve and write as a coordinate point.
5x+4y=-14
3x+6y=6
Please help and thanks
3 answers
well, I think I would multiply the first one by three and the second one by two
15 x + 12 y = -42
6 x + 12 y = 12
------------------ subtract
9 x = -54 or x = -6
then
-18 + 6 y = 6
6 y = 24
y = 4
(-6 , 4 )
15 x + 12 y = -42
6 x + 12 y = 12
------------------ subtract
9 x = -54 or x = -6
then
-18 + 6 y = 6
6 y = 24
y = 4
(-6 , 4 )
John's error, after multiplying by 3 , should be
15x + 12y = -42 , John had +42
15x + 12y = -42 , John had +42