How do you solve #x + 4y = 19# and #y = -2x - 4#?

1 Answer
May 18, 2018

Answer:

#(x,y)to(-5,6)#

Explanation:

#x+4y=19to(1)#

#y=-2x-4to(2)#

#"substitute "y=-2x-4" into equation "(1)#

#x+4(-2x-4)=19larrcolor(blue)"distribute"#

#rArrx-8x-16=19#

#rArr-7x-16=19#

#"add 16 to both sides"#

#rArr-7x=19+16=35#

#"divide both sides by "-7#

#rArrx=35/(-7)=-5#

#"substitute "x=-5" into equation "(2)#

#rArry=(-2xx-5)-4=10-4=6#

#"the point of intersection of the 2 equations "=(-5,6)#
graph{(y+1/4x-19/4)(y+2x+4)=0 [-20, 20, -10, 10]}