Question

$$\left. \begin{array} { l } { \frac { 11 } { ( x - 1 ) ( 2 x + 3 ) \leq 0 } } \\ { - ( x - 1 ) ( 2 x + 3 ) \leq 0 } \\ { x - 3 x ^ { 2 } + 2 x + 2 } \\ { + ( 6 x + 1 ) ^ { 2 } - ( n ) ^ { 2 } - ( n - 1 ) ^ \right.$$

Answer

(-1-sqrt(18601))/4<=x<=(-1+sqrt(18601))/4

Solution


Expand.
\[2{x}^{2}+3x-2x-3\le 02322\]
Simplify  \(2{x}^{2}+3x-2x-3\)  to  \(2{x}^{2}+x-3\).
\[2{x}^{2}+x-3\le 02322\]
Move all terms to one side.
\[2{x}^{2}+x-3-02322\le 0\]
Simplify  \(2{x}^{2}+x-3-02322\)  to  \(2{x}^{2}+x-2325\).
\[2{x}^{2}+x-2325\le 0\]
Use the Quadratic Formula.
\[x=\frac{-1+\sqrt{18601}}{4},\frac{-1-\sqrt{18601}}{4}\]
From the values of \(x\) above, we have these 3 intervals to test.
\[\begin{aligned}&x\le \frac{-1-\sqrt{18601}}{4}\\&\frac{-1-\sqrt{18601}}{4}\le x\le \frac{-1+\sqrt{18601}}{4}\\&x\ge \frac{-1+\sqrt{18601}}{4}\end{aligned}\]
Pick a test point for each interval.
For the interval \(x\le \frac{-1-\sqrt{18601}}{4}\):
Let's pick \(x=-35\). Then, \((-35-1)(2\times -35+3)\le 02322\).After simplifying, we get \(2412\le 1234\), which is
false
.
Drop this interval.
.
For the interval \(\frac{-1-\sqrt{18601}}{4}\le x\le \frac{-1+\sqrt{18601}}{4}\):
Let's pick \(x=0\). Then, \((0-1)(2\times 0+3)\le 02322\).After simplifying, we get \(-3\le 1234\), which is
true
.
Keep this interval.
.
For the interval \(x\ge \frac{-1+\sqrt{18601}}{4}\):
Let's pick \(x=34\). Then, \((34-1)(2\times 34+3)\le 02322\).After simplifying, we get \(2343\le 1234\), which is
false
.
Drop this interval.
.
Therefore,
\[\frac{-1-\sqrt{18601}}{4}\le x\le \frac{-1+\sqrt{18601}}{4}\]