Question #4e3ef

2 Answers
Apr 11, 2017

Answer:

#x=7#, #y=-16#

Explanation:

#color(white)(-)x+y=-9#
#color(white)(-)#
#x+2y=-25#

Let's use elimination here. We can subtract both equations to remove the #x#:
#color(white)(-)cancel(x)+y=-9#
#color(black)(-)#
#cancel(x)+2y=-25#
.......................................
#-y=16#
#y=-16#

Now let's solve for #x# by replacing #y# with #-160.#
#x+y=-9#
#x+(-16)=-9#
Add #16# on both sides
#x=7#

Just to double check our work, we'll solve the second problem using #7# and #-16# for #x# and #y#, respectively.
#x+2y=-25#
#7+ 2*(-16)# should equal #-25#
#7-32=12#
#12=12#
We were right! Good job!

Apr 11, 2017

Answer:

#color(blue)(x=7#

Explanation:

#x+y=-9-----(1)#

#x+2y=-25-----(2)#

#(1) xx 2##2x+2y=-18----(3)#

#(2)-(3)##-x=-7#

#color(blue)(x=7#

sustitute #x=7# in #(2)#

#7+2y=-25#

#2y=-25-7#

#2y=-32#

#y=-32/2#

#y=-16#

Check:

substitute #color(blue)(x=7# and #color(blue)(y=-16 # in #(1)#

#color(blue)7+(color(blue)-16)=-9#

#-9=-9#