Solve the linear system of equations using the linear combination method
4x +5y=7
y=3x+9
enter your answers in the boxes.
x=
y=

x = -2

y = 3

Step-by-step explanation:

Write the system the following way:

4x + 5y = 7

-3x +y  = 9

we need to eliminate one unknown by multiplying one equation for a suitable number in such a way that when we add the equations one unknown is eliminated.

If we multiply the second eq. by -5 the y is eliminated

4x + 5y = 7

15x -5y = -45

add the equations

19x = -38 ===> x = -38/19 ===> x = -2

Now replace this value in any equation to get y. For example, in 1st one.

4(-2) + 5y = 7 ===> -8 +5y = 7 ===> 5y = 7+8 ===> 5y = 15 ===> y = 15/5 ===>

y=3

12

step-by-step explanation:

12 + 5 = 17

12x2=24

24-7=17

image for option 4

step-by-step explanation:

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