4x+9y=-30 -6x+4y=10

Question

how do u solve the equation?

Answer 1

Hi Veronica, there are two equations in two unknowns, we can solve this type of system by elimination or substitution.

 

 4x + 9y  = -30

-6x + 4y  =  10

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To solve by elimination, multiply the first equation by 3 and the second equation by 2. This will eliminate the x term.

 

 12x + 27y  = -90

-12x +  8y  =   20

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          35y  = -70

 

Divide both sides by 35:

 

y = -2

 

Substitute for y in the first equation to find x:

 

4x + (9 * -2) = -30

 

4x - 18 = -30

 

Add -18 to both sides:

 

4x = -12

 

Divide both sides by 4:

 

x = -3

 

To check, substitute for x and y in the second equation:

 

(-6 * -3) + (4 * -2) = 10

 

18 - 8 = 10

 

10 = 10, values check.

 

Questions?