X+3y+2=0,4y+2x=k,x-2y=3 Find the value of k if the following equation are consistent?

1 Answer
May 23, 2018

#k=-2#

Explanation:

Since equations are consistent, we find values of #x# and #y# first and then substitute them in the equation to find value of #k#.

#x+3y+2 = 0# -------> equation 1
#4y+2x=k# ----------> equation 2
#x-2y=3# ------------> equation 3

From equation 1; make #x# the subject.

#x-2y=3#
#color(red)(x=3+2y)#

Substitute #x=3+2y# in equation 1

#x+3y+2=0#

#color(red)((3+2y))+3y+2=0#

#3+2y+3y+2=0#

#3+5y+2=0#

#5y=-2-3#

#5y=-5#

#color(red)(y=-1)#

Now, substitute value of #y=-1# in equation 3 to get value of #x#

#x-2y=3#

#x-2(-1)=3#

#x+2=3#

#x=3-2#

#color(red)(x=1)#

Check the answer of values of #x# and #y# before finding value of #k#

#x+3y+2=0#

#1+3(-1)+2=0#

#1-3+2=0#

#-2+2=0# ------> so values of #x# and #y# are correct.

Final step is to substitute values of #x# and #y# in equation 2 to find value of #k#:

#4y+2x=k#

#4(-1) + 2(1)=k#

#-4+2=k#

#-2=k#

Therefore, #color(red)(k = -2)#