Question 178718
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{{{2x-y=10}}}, EQN 1
{{{x=-2y}}}, EQN 2
Subst. EQN 2 in EQN 1:
{{{2(-2y)-y=10}}}
{{{-4y-y=10}}}
{{{-5y=10}}}--------->{{{cross(-5)y/cross(-5)=cross(10)2/cross(-5)}}}
{{{highlight(y=-2)}}}, subst. in EQn 2:
{{{x=-2(-2)=highlight(4=x)}}}
Check via EQN 1:
{{{2(4)-(-2)=10}}}
{{{8+2=10}}}
{{{10=10}}}
Thank you,
Jojo</pre>