How do solve the following linear system?: # 5x-y=3 , x+y=-4 #?

1 Answer
Jul 12, 2016

Answer:

#x = -1/6," "y = -3 5/6#

Explanation:

An alternative method is to write each equation with y as the subject. Both equations allow this to be done easily.

#y = 5x-3 " and "y = -x-4#

And now by equating the #y#'s, we get
#y = y#

#:.5x-3 =-x-4#

#6x = -1 rArr " "x = -1/6#

There are now two equations to calculate a value for #y#,which is quite nifty, because we can then check that each equation gives the same value for #y#.

#y = 5(-1/6) -3 = -3 5/6#
#y = -(-1/6)-4 = -3 5/6#