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Intern
Joined: 29 May 2015
Posts: 10

Re: If equation x/2 + y/2 = 5 enclose a certain region
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22 Sep 2015, 23:35
I think there is a pattern for this sort of problem.
1. x<0 and y<0 > −x−y=10 > y=−10−x;
2. x<0 and y≥0 > −x+y=10 > y=10+x;
3. x≥0 and y<0 > x−y=10 > y=x−10;
4. x≥0 and y≥0 > x+y=10 > y=10−x;
From above, we see that 1 & 4 are parallel, since they have the same slope, as this would be the case for 2 & 4. From above, we see that intersection points on x and yaxis is 10 and 10.
If you get to this far, you know it is a sqaure.
Afterwards, as written by many ppl, it is just finding an area of a square, 200.



Manager
Joined: 18 Apr 2018
Posts: 93

Re: If equation x/2 + y/2 = 5 enclose a certain region
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09 Jul 2018, 05:16
Hi guys, really good explanation. Totally get it. I have a question though, Is it possible to solve this in less than 3 mins because I spent about 5mins on it.
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Intern
Joined: 10 Jun 2019
Posts: 9

Re: If equation x/2 + y/2 = 5 enclose a certain region
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17 Jun 2019, 04:55
Approach the question by trying to find the intercept of the equations. So when y=0 => x/2=5 => x = 10 and 10. Similarly, when x=0 => y/2=5 => y = 10 or 10. So we get an area bounded by the above intercepts and symmetrical about the xy axis. Therefore we can find the area of 1 region and multiply by 4 to get the total area. Area of one region = 1/2*10*10 = 50. Total area = 50*4 = 200. Option D is the right answer.




Re: If equation x/2 + y/2 = 5 enclose a certain region
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17 Jun 2019, 04:55



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