How do you solve the system using elimination $c + 2d = -2$ and $-2c - 5d = 3$ ?

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Answer 1 · 2015-06-08T17:23:52

$c +2d = -2$ , multiplying this equation with $2$
$2c +4d = -4$ ..........equation $(1)$

$−2c−5d=3$ ...............equation $(2)$

Adding the two equations to cancel $color(red)(2c$

$cancelcolor(red)(2c) +4d = -4$
$cancelcolor(red)(-2c) - 5d =3$

$-d = -1$
$color(red)(d=1$

Substituting $d$ in the first equation to find $c$

$c = -2 -2d$
$c = -2-2.(1)$
$color(red)( c = -4$

The solutions for the system of equations are:
$color(red)( d=1, c=-4$

How do you solve the system using elimination c + 2d = -2c + 2d = -2 and -2c - 5d = 3-2c - 5d = 3?