SOLUTION: System of Linear Equations Read and solve for the values of the unknown using the suggested method. show the solutions. 2.By Substitution method: 4x + 5y = -8 3x + y = 5

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: System of Linear Equations Read and solve for the values of the unknown using the suggested method. show the solutions. 2.By Substitution method: 4x + 5y = -8 3x + y = 5      Log On


   



Question 1172191: System of Linear Equations
Read and solve for the values of the unknown using the suggested method.
show the solutions.
2.By Substitution method:
4x + 5y = -8
3x + y = 5

Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
4x + 5y = -8
3x + y = 5
solve for y in the second equation to get:
y = 5 - 3x
replace y in the first equation with that to get:
4x + 5 * (5 - 3x) = -8
simplify to get:
4x + 25 - 15x = -8
subtract 25 from both sides of the equation to get:
4x - 15x = -8 - 25
combine like terms to get:
-11x = -33
solve for x to get:
x = 3
replace x in either original equation with 3 to get:
4x + 5y = -8 becomes:
4*3 + 5y = -8 which becomes
12 + 5y = -8
subtract 12 from both sides of the equation to get:
5y = -20
solve for y to get:
y = -4
you have:
x = 3
y = -4
confirm by replacing x and y in both original equations to get:
4x + 5y = -8 becomes 12 - 20 = -8 which becomes -8 = -8 which is true.
3x + y = 5 becomes 9 - 4 = 5 which becomes 5 = 5 which is true.
both equations are true when x = 3 and y= -4.
your solution is that the value of x is 3 and the value of y is -4.