How do you solve the system $x = - 2 y - 1$ $x = −2y − 1$ and $2 x + y = - 20$ $2x + y = −20$ ?

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How do you solve the system $x = - 2 y - 1$ $x = −2y − 1$ and $2 x + y = - 20$ $2x + y = −20$ ?

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Answer 1 · 2015-05-27T18:20:00

Given
$[1] x = - 2 y - 1$ $"[1] "x=-2y-1$
$[2] 2 x + y = - 20$ $"[2] "2x+y = -20$

We can substitute for $x$ $x$ in [2] the expression for $x$ $x$ in [1]
$[3] 2 (- 2 y - 1) + y = - 20$ $"[3] "2(-2y-1)+y = -20$
Simplifying
$[4] - 3 y - 2 = - 20$ $"[4] "-3y -2 = -20$
which implies
$[5] y = 6$ $[5] "y=6$

Substituting the value for $y$ $y$ back into [1]
$[6] x = - 2 (6) - 1$ $"[6] "x = -2(6) -1$
implying
$[7] x = - 13$ $"[7] "x = -13$

Solution is $(x, y) = (- 13, 6)$ $(x,y) = (-13,6)$

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How do you solve the system $x = - 2 y - 1$ $x = −2y − 1$ and $2 x + y = - 20$ $2x + y = −20$ ?

1 Answer

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Science

Math

Humanities

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How do you solve the system x=−2y−1x = −2y − 1 and 2x+y=−202x + y = −20?

1 Answer

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How do you solve the system $x = - 2 y - 1$ $x = −2y − 1$ and $2 x + y = - 20$ $2x + y = −20$ ?