How do you solve y= 3/4x+3 and 2x-4y=6?

2 Answers
Sep 9, 2015

Answer:

#(x, y) = (-18, -21/2)#

Explanation:

Given
[1]#color(white)("XXX")y=3/4x+3#
[2]#color(white)("XXX")2x-4y=6#

Using [1], substitute #3/4x+3# for #y# in [2]
[3]#color(white)("XXX")2x-4(3/4x+3) = 6#

[4]#color(white)("XXX")2x-3x-12 = 6#

[5]#color(white)("XXX")-x = 18#

[6]#color(white)("XXX")x = -18

Substitute #(-18)# for #x# in[2]
[7]#color(white)("XXX")2(-18)-4y=6#

[8]#color(white)("XXX")-4y = 42#

[9]#color(white)("XXX")y = -21/2#

Sep 9, 2015

Answer:

#x=-18#
#y=-21/2#

Explanation:

#y=3/4x+3#---------------(1)
#2x-4y=6#-----------------(2)

Substitute the value of y from equation (1) in equation (2)

#2x -4(3/4x+3)=6#
#2x-3x-12=6#
#-x=6+12=18#
#x=-18#

Substitute x value in equation (2)

#2(-18) -4y = 6#
#-36-4y = 6#
#-4y = 6 + 36 = 42#
#y = 42/-4 = -21/2#