First, I would get rid of the decimals. It will make life easier. So, multiply both sides of each equation by 10.
(That is perfectly legal as long as you do it to both sides of an equation).
2x - 5y = -278
3x + 4y = 687
Our goal is to eliminate either the x or the y.
Since the y's have opposite signs, you might decide it is easier to eliminate y.
To eliminate the y's you will need a -20 and +20 (since 4 times 5 = 20)
Multiply the first equation by 4 and the 2nd equation by 5.
Now, add the coefficients for the x term and add the constants on the other side of the equal sign.
Solve for x by dividing both sides by the coefficient of x.
You now, have the value for x. Substitute that value for x into one of the original equations and solve for y.
Be sure to check in both equations to be sure you haven't made a mistake.
I will be happy to check your final answers or help more along the way if you need additional help.
Solve each system by using the elimination method. Make sure to write your answer in (x,y) form.
0.2x - 0.5y = -27.8
0.3x + 0.4y = 68.7
1 answer
1 answer