SOLUTION: solve by substitution method 9x+4y= -55 -7x+y= 51

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Question 212812: solve by substitution method
9x+4y= -55
-7x+y= 51

Found 2 solutions by drj, MathTherapy:
You can put this solution on YOUR website!
Solve by substitution method

Use the following steps to solve the above system of equations:

Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
We'll use substitution. After moving 4*y to the right, we get:
, or . Substitute that
into another equation:
and simplify: Error: 'Can't call method "invoke_solver" on an undefined value at /home/ichudov/project_locations/algebra.com/templates/Algebra/Solver/PerlSolver.pm line 115. Can't call method "invoke_solver" on an undefined value at /home/ichudov/project_locations/algebra.com/templates/Algebra/Solver/PerlSolver.pm line 115. '. Can't call method "invoke_solver" on an undefined value at /home/ichudov/project_locations/algebra.com/templates/Algebra/Solver/PerlSolver.pm line 115. Can't call method "invoke_solver" on an undefined value at /home/ichudov/project_locations/algebra.com/templates/Algebra/Solver/PerlSolver.pm line 115.
error_location: 101

I hope the above steps were helpful.

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Respectfully,
Dr J
You can put this solution on YOUR website!
9x + 4y = -55 ------ eq (i)
-7x + y = 51 ------ eq (ii)

Solve eq (ii) for y ------> -7x + y = 51 becomes y = 7x + 51

Substitute 7x + 51 for y in eq (i) 9x + 4y = -55 becomes

9x + 4(7x + 51) = -55

9x + 28x + 204 = -55

37x = -259

Substitute - 7 for x in eq (ii) -7x + y = 51 becomes

-7(-7) + y = 51

49 + y = 51

y = 2

Therefore, the solution set is (,)