How do you solve by substitution x=3-3yx=3−3y and 4y=x+114y=x+11?

1 Answer
Jim G.
Mar 8, 2018

(x,y)to(-3,2)(x,y)→(−3,2)

Explanation:

x=3-3yto(1)x=3−3y→(1)

4y=x+11to(2)4y=x+11→(2)

"since equation "(1)" gives x in terms of y we can "color(blue)"substitute ""it directly into equation "(2)since equation (1) gives x in terms of y we can substitute it directly into equation (2)

4y=3-3y+114y=3−3y+11

"add 3y to both sides"add 3y to both sides

4y+3y=3cancel(-3y)cancel(-3y)+11

rArr7y=14

"divide both sides by 7"

(cancel(7) y)/cancel(7)=14/7

rArry=2

"substitute "y=2" into equation "(1)

x=3-(3xx2)=-3

"solution is "x=-3" and "y=2

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