Question #29fca

1 Answer
Nov 3, 2017

#x=3 and y=-1#

Explanation:

First, as there are 2 unknowns in the question, we can find the relationship bewteen the 2 unknowns, like #x= ?#

In this question,
#x-y=4 # .......... #(1)#
#x^2-y^2=8# ..........#(2)#

From #(1)#, we know that #x=4+y#.........#(3)#
Then, we can sub #(3)# into #(2)#,
#(4+y)^2-y^2 =8#
#4^2+2*4*y+y^2-y^2=8#
#16 +8y=8#
#8y=-8#
#y=-1#

We get the value of #y#, but we still don't know #x#, so we can sub #y=-1# into #(3)#
#x=4+y=4+(-1)=4-1=3#

Here we get #x=3 and y=-1# and it's the answer. Hope this can help you :)