SOLUTION: 1 number is equal to the square of another. Find the numbers if both are positive and their sum is 1980.

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Question 739932: 1 number is equal to the square of another. Find the numbers if both are positive and their sum is 1980.
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

1 number x is equal to the square of another y.
x=y%5E2......eq.1

Find the numbers if both are positive and their sum is x%2By=1980......eq.2

x=y%5E2......eq.1
x%2By=1980......eq.2
__________________________ solve the system
x%2By=1980......eq.2...substitute x from eq.1
y%5E2%2By=1980......eq.2
y%5E2%2By-1980=0.....use quadratic formula

y+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+

y+=+%28-1+%2B-+sqrt%28+1%5E2-4%2A1%2A%28-1980%29+%29%29%2F%282%2A1%29+

y+=+%28-1+%2B-+sqrt%28+1%2B7920+%29%29%2F2+

y+=+%28-1+%2B-+sqrt%28+7921+%29%29%2F2+

y+=+%28-1+%2B-+89%29%2F2+
we need only positive solution because given the numbers are both positive

y+=+%28-1+%2B+89%29%2F2+
y+=++88%2F2+
highlight%28y+=++44%29+

find x

x=y%5E2......eq.1
x=44%5E2
highlight%28x=1936%29

check their sum:

x%2By=1980......eq.2
1936%2B44=1980
1980=1980