How do you solve the system of equations #4x - 3y = - 4# and #y = - x + 6#?

1 Answer
May 31, 2017

See a solution process below:

Explanation:

Step 1) Because the second equation is already solved for #y# we can substitute #(-x + 6)# for #y# in the first equation and solve for #x#:

#4x - 3y = -4# becomes:

#4x - 3(-x + 6) = -4#

#4x - (3 xx -x) - (3 xx 6) = -4#

#4x - (-3x) - 18 = -4#

#4x + 3x - 18 = -4#

#(4 + 3)x - 18 = -4#

#7x - 18 = -4#

#7x - 18 + color(red)(18) = -4 + color(red)(18)#

#7x - 0 = 14#

#7x = 14#

#(7x)/color(red)(7) = 14/color(red)(7)#

#(color(red)(cancel(color(black)(7)))x)/cancel(color(red)(7)) = 2#

#x = 2#

Step 2) Substitute #2# for #x# in the second equation and calculate #y#:

#y = -x + 6# becomes:

#y = -2 + 6#

#y = 4#

The solution is: #x = 2# and #y = 4# or #(2, 4)#