How do you solve the following system: x - 3y = -1 , 4x+y=-7 x−3y=−1,4x+y=−7?

2 Answers
Roopali
Apr 8, 2018

x=-22/13x=−2213
y= -9/39y=−939

Explanation:

x - 3y = -1x−3y=−1
3(4x + y = -7)3(4x+y=−7)

x-3y = -1x−3y=−1
12x+3y = -2112x+3y=−21

13x = -2213x=−22
x = (-22/13)x=(−2213)

(-22/13) - 3y = -1(−2213)−3y=−1
-1 + 22/13 = -3y−1+2213=−3y
(-13+22)/13 = -3y−13+2213=−3y
9/13 *1/-3 = y913⋅1−3=y
y= -(9/39)y=−(939)

Lucy
Apr 8, 2018

x=-22/13x=−2213
y=-3/13y=−313

Explanation:

x-3y=-1x−3y=−1 --- (1)
4x+y=-74x+y=−7 --- (2)

From (1),

x=3y-1x=3y−1 --- (3)

Sub (3) into (2)

4(3y-1)+y=-74(3y−1)+y=−7
12y-4+y=-712y−4+y=−7
13y=-313y=−3
y=-3/13y=−313 --- (4)

Sub (4) into (3)

x=3(-3/13)-1x=3(−313)−1
x=-22/13x=−2213

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