How do you solve x+y = 4x+y=4 and y=x+4y=x+4?

1 Answer
Don't Memorise
Aug 3, 2015

The solution for the system of equations is
color(blue)(x=0,y=4x=0,y=4

Explanation:

x+y=4 x+y=4
x=color(blue)(4-yx=4−y....equation (1)(1)

y=x+4y=x+4.....equation (2)(2)

Solving by substitution:

Substituting equation 11 in equation 22 to find yy
y=x+4y=x+4
y=4-y+4y=4−y+4
2y=82y=8
color(blue)(y=4y=4

Substitute yy in equation 11 to find xx
x=4-yx=4−y
x=4-4x=4−4
color(blue)(x=0x=0

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