Question:

If $\frac{x^{2}+2x+7}{2x+3} < 6, x\,\in\,R, $ then

Updated On: Aug 19, 2024
  • $x >11$ or $x < -\frac{3}{2}$
  • $x > 11$ or $x < -1$
  • $ -\frac{3}{2} < x < -1$
  • $ -1 < x < 11$ or $x < -\frac{3}{2}$
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The Correct Option is D

Solution and Explanation

Given, $\frac{x^{2}+2 x+7}{2 x+3}<6$
$\Rightarrow \frac{x^{2}+2 x+7}{2 x+3}-6<0$
$\Rightarrow \frac{x^{2}-10 x-11}{2 x+3}<0$
$\Rightarrow \frac{(x-11)(x+1)}{2 x+3}<0$
$\Rightarrow \frac{(x-11)(x+1)(2 x+3)}{(2 x+3)^{2}}<0$
$\Rightarrow (x-11)(x+1)(2 x+3) < 0$
$\Rightarrow x \in\left(-\infty,-\frac{3}{2}\right) \cup(-1,11)$
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Concepts Used:

Quadratic Equations

A polynomial that has two roots or is of degree 2 is called a quadratic equation. The general form of a quadratic equation is y=ax²+bx+c. Here a≠0, b, and c are the real numbers

Consider the following equation ax²+bx+c=0, where a≠0 and a, b, and c are real coefficients.

The solution of a quadratic equation can be found using the formula, x=((-b±√(b²-4ac))/2a)

Two important points to keep in mind are:

  • A polynomial equation has at least one root.
  • A polynomial equation of degree ‘n’ has ‘n’ roots.

Read More: Nature of Roots of Quadratic Equation

There are basically four methods of solving quadratic equations. They are:

  1. Factoring
  2. Completing the square
  3. Using Quadratic Formula
  4. Taking the square root