.
y = 15-3x
Hence, x^2 + y^2 = x^2 + (15-3x)^2 = x^2 + 225 - 90x + 9x^2 = 10x^2 - 90x + 225.
A quadratic function ax^2 + bx + c with positive coefficient "a" has the minimum at x = .
In your case, a = 10 and b = -90, hence x = - = .
Then y = = = .
ANSWER. This pair is (x,y) = (,).
Solved.
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On finding the maximum/minimum of a quadratic function, see the lessons
- HOW TO complete the square to find the minimum/maximum of a quadratic function
- Briefly on finding the minimum/maximum of a quadratic function
- HOW TO complete the square to find the vertex of a parabola
- Briefly on finding the vertex of a parabola
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this textbook under the topic "Finding minimum/maximum of quadratic functions".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.