SOLUTION: Hello, this question loses me, I tried setting this up in a y=x^2+z^2 format and substituting but I get lost very quickly. QUESTION: "Find two non-negative numbers whose sum is

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Question 663417: Hello, this question loses me, I tried setting this up in a y=x^2+z^2 format and substituting but I get lost very quickly.
QUESTION: "Find two non-negative numbers whose sum is 18.5 and the sum of their squares is a minimum."
I had
x^2+(18.5-x)^2
=x^2+342.25-37x+x^2
=2x^2-37x+342.25
and then I got very lost. Someone suggested I used -b/2a to help me solve but I'm not sure what I'm supposed to do.
Thanks for the help in advance!

Found 2 solutions by Alan3354, josmiceli:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
QUESTION: "Find two non-negative numbers whose sum is 18.5 and the sum of their squares is a minimum."
I had
x^2+(18.5-x)^2
=x^2+342.25-37x+x^2
=2x^2-37x+342.25
and then I got very lost. Someone suggested I used -b/2a to help me solve but I'm not sure what I'm supposed to do.
-------------------------------
f(x) = 2x^2-37x+342.25
The min is the vertex of the parabola, at x = -b/2a
x = -(-37)/4 = 9.25
f(9.25) is the minimum
= 171.25

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Suppose I vary one of the numbers and hold
the other number fixed, but not saying
right away what it is fixed at.
Let the variable number = +x+
Let the fixed number = +a+
given:
+x+%2B+a+=+18.5+
+f%28x%29+=+x%5E2+%2B+a%5E2+
--------------------
+a+=+18.5+-+x++
+f%28x%29+=+x%5E2+%2B+%28+18.5+-+x+%29%5E2+
+f%28x%29+=+x%5E2+%2B+342.25+-+37x+%2B+x%5E2+
+f%28x%29+=+2x%5E2+-+37x+%2B+342.25+ ( just what you got )
-----------------------------
This is in the form +ax%5E2+%2B+bx+%2B+c+, so the
minimum is at +-b%2F%282a%29+
+a+=+2+
+b+=+-37+
+-b%2F%282a%29+=+-%28-37%29+%2F+%282%2A2%29+
+-b%2F%282a%29+=+37%2F4+
+37%2F4+=+9.25+
and
+a+=+18.5+-+x++
+a+=+18.5+-+9.25+
+a+=+9.25+
Both numbers are 9.25
check:
+2%2A9.25%5E2++=+171.125+
-----------------------
What if the numbers are
9.24 and 9.26
+9.24%5E2+%2B+9.26%5E2+=+85.3776+%2B+85.7476+
+85.3776+%2B+85.7476+=+171.1252+
This is higher than +2%2A9.25%5E2+
So we have a minimum