Extreme polynomial

Algebra Level 2

3 x 2 + 6 x + 7 + 5 x 2 + 10 x + 14 = 4 2 x x 2 x = ? \large { \sqrt { 3{ { x }^{ 2 } }+6x+7 } +\sqrt { 5{ x }^{ 2 }+10x+14 } =4-2x-{ x }^{ 2 } \\ x = \ ? }

-1 0 No solution exist x ( 1 , 1 ) x\in (-1,1) 1

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

M Dub
Aug 4, 2015

3x^2 + 6x + 7= 3(x+1)^2 + 4, so sqrt (3x^2 + 6x + 7) >= 2.

5x^2 + 10x +14 = 5(x+1)^2 + 9, sqrt(5x^2 + 10x +14) >= 3.

The left hand side >=5.

4-2x-x^2 = 4 -(x+1)^2 +1 = 5-(x+1)^2 <= 5.

The right hand side <=5.

The solution exists only when (x+1)^2=0, so x=-1.

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...