Difference between revisions of "2012 MPFG Problem 8"

(Note)
(Note)
Line 5: Line 5:
 
We can actually think of this question through its analytic geometric meaning/ As shown, the <math>1st</math> equation creates a plane made by connecting the points <math>(3,0,0)</math>, <math>(0,3,0)</math>, and <math>(0,0,3)</math>. The <math>2nd</math> equation creates a sphere with radius <math>\sqrt{6}</math> and a center at <math>(0,0,0)</math>. The intersections of the <math>2</math> equations create a circle. We want the maximum value of <math>z</math>, which is obviously located on the "axis of symmetry" of the graph.
 
We can actually think of this question through its analytic geometric meaning/ As shown, the <math>1st</math> equation creates a plane made by connecting the points <math>(3,0,0)</math>, <math>(0,3,0)</math>, and <math>(0,0,3)</math>. The <math>2nd</math> equation creates a sphere with radius <math>\sqrt{6}</math> and a center at <math>(0,0,0)</math>. The intersections of the <math>2</math> equations create a circle. We want the maximum value of <math>z</math>, which is obviously located on the "axis of symmetry" of the graph.
  
[[File:Hihihi.jpg|710px|center]]
+
[[File:Hihihi.jpg|550px|center]]

Revision as of 02:29, 22 August 2025

Problem

Suppose that $x$, $y$, and $z$ are real numbers such that $x + y + z = 3$ and $x^{2} + y^{2} + z^{2} = 6$. What is the largest possible value of $z$? Express your answer in the form $a +\sqrt{b}$, where $a$ and $b$ are positive integers.

Note

We can actually think of this question through its analytic geometric meaning/ As shown, the $1st$ equation creates a plane made by connecting the points $(3,0,0)$, $(0,3,0)$, and $(0,0,3)$. The $2nd$ equation creates a sphere with radius $\sqrt{6}$ and a center at $(0,0,0)$. The intersections of the $2$ equations create a circle. We want the maximum value of $z$, which is obviously located on the "axis of symmetry" of the graph.

Hihihi.jpg