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Solve the system of two equations in two variables1) 6x - 7y = 28 2x + 4y = -16

User SBH
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1 Answer

9 votes
9 votes

x = 0, and y = -4

6x - 7y = 28 ................................. equation 1

2x + 4y = -16.................................. equation 2

so we need to eliminate one of the variable before i can get the other variable

so let eliminate x first

to eliminate x we need to make the coefficient of x in both equations equal

so, to do that we need to multiply equation 1 by 1 and multiply equation 2 by 3

6x - 7y = 28 multiply by 1

2x + 4y = -16 multiply by 3

6x*1 - 7y*1 = 28*1

2x*3 + 4y*3 = -16*3

6x - 7y = 28 ..................... equation 3

6x + 12y = -48 ........................equation 4

so, we can solve equation 3 and 4 simultaneously

to eliminate x we will substract equation 4 from 3

6x - 7y = 28

-

6x + 12y = -48

6x - 6x = 0

-7y - (12y) = -19y

28 - (-48) = 76

we have successfully eliminate x

we have, -19y = 76

-19y = 76

dividing both sides by -19

-19y/19 = 76/-19

y = -4

To solve for x we can put y= -4 in either equation 1 or equation 2

so let us try equation 2, then you will try equation 1

equation 2 is 2x + 4y = -16

since y= -4

2x + 4(-4) = -16

2x -16 = -16

2x = -16 +16

2x = 0

x = 0/2

x = 0

User Gruenewa
by
2.9k points
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