How do you solve the following system?: 4x+9y=−4,−21x+2y=4

1 Answer
Lucy
May 30, 2018

x=−44197
y=−68197

Explanation:

4x+9y=−4 --- (1)
−21x+2y=4 --- (2)

From (1),
4x+9y=−4
4x=−4−9y
x=14(−4−9y) --- (3)

Sub (3) into (2)

−21(14(−4−9y))+2y=4
−214(−4−9y)+2y=4
21+1894y+2y=4
1974y=−17
y=−17×4197
y=−68197 --- (4)

Sub (4) into (3)
x=14(−4−(9×−68197))
x=−44197

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