Question

Solve the system of equations using multiplication.
3x + 8y = –20
5x – y = –19

Answer 1

[tex]3x + 8y = -20[tex]

[tex]5x - y = -19[tex]

[tex]3x + 8y = -20[tex]

[tex]40x - 8y = -152[tex] (multiply both sides by 8)

Add the two equations together.

[tex](3x + 8y) + (40x - 8y) = -20 + (-152)[tex]

Which makes it

[tex]43x = -172[tex]

Then divide 43 by both sides.

[tex]x = -4[tex]

Then get [tex]y[tex] by substituting [tex]x[tex]

[tex]5 * (-4) - y = -19[tex]

And solve the equation.

[tex]5 * (-4) - y = -19[tex]

[tex]5 * (-4) - (-19) = y[tex]

[tex]-20 + 19 = y[tex]

[tex]y = -1[tex]

So the answer is:

[tex]x = -4 , y = -1[tex]