SOLUTION: when a positive number is added to its square,the sum is 240.find the number

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Question 712158: when a positive number is added to its square,the sum is 240.find the number
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let the positive number = +n+
It's square is +n%5E2+
given:
+n+%2B+n%5E2+=+240+
Subtract +240+ from both sides
+n%5E2+%2B+n+-+240+=+0+
Note that +15%2A16+=+240+, so
+%28+n+%2B+16+%29%2A%28+n+-+15+%29+=+0+
The solutions are:
+n+=+-16+ and
+n+=+15+
The number has to be positive, so
+n+=+15+
check:
+n+%2B+n%5E2+=+240+
+15+%2B+15%5E2+=+240+
+15+%2B+225+=+240+
+240+=+240+
OK