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x-y-67-x-ay-7-




Question Number 4690 by thachan last updated on 21/Feb/16
x+y=67  x−ay=7
$${x}+{y}=\mathrm{67} \\ $$$${x}−{ay}=\mathrm{7} \\ $$
Answered by 123456 last updated on 21/Feb/16
−x+ay=−7  (a+1)y=60  y=((60)/(a+1))  x=7+ay  x=7+((60a)/(a+1))  x=((67a+7)/(a+1)),y=((60)/(a+1))  x+y=((67(a+1))/(a+1))=67  x−ay=((7(a+1))/(a+1))=7,a≠−1
$$−{x}+{ay}=−\mathrm{7} \\ $$$$\left({a}+\mathrm{1}\right){y}=\mathrm{60} \\ $$$${y}=\frac{\mathrm{60}}{{a}+\mathrm{1}} \\ $$$${x}=\mathrm{7}+{ay} \\ $$$${x}=\mathrm{7}+\frac{\mathrm{60}{a}}{{a}+\mathrm{1}} \\ $$$${x}=\frac{\mathrm{67}{a}+\mathrm{7}}{{a}+\mathrm{1}},{y}=\frac{\mathrm{60}}{{a}+\mathrm{1}} \\ $$$${x}+{y}=\frac{\mathrm{67}\left({a}+\mathrm{1}\right)}{{a}+\mathrm{1}}=\mathrm{67} \\ $$$${x}−{ay}=\frac{\mathrm{7}\left({a}+\mathrm{1}\right)}{{a}+\mathrm{1}}=\mathrm{7},{a}\neq−\mathrm{1} \\ $$

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