Chapter 3: Q. 8 (page 171)

In problems 7-22, solve the inequality.
$x^{2} + 3 x - 10 > 0$

Short Answer

Expert verified

The solution set of the inequality is $(- \infty, - 5) o r (2, \infty)$ .

Step by step solution

Step 1. Given Information

The given inequality is $x^{2} + 3 x - 10 > 0$

Step 2. Find the intercepts and vertex

The value of $f (0) = - 10$ .
So, the y-intercept is $(0, - 10)$ .
Factor the equation $f (x) = 0$ .

$\begin{array}{rcl} x^{2} + 3 x - 10 & = & 0 \\ (x + 5) (x - 2) & = & 0 \end{array}$

Equate the factors to 0.

$\begin{array}{rcl} x + 5 & = & 0 \\ x & = & - 5 \\ x - 2 & = & 0 \\ x & = & 2 \end{array}$

So, the x-intercepts are $(- 5, 0), (2, 0)$ .
The vertex of the parabola exists at $\frac{- b}{2 a} = \frac{- 3}{2 (1)} = \frac{- 3}{2}$
Find the value of function at $x = \frac{- 3}{2}$ .

$\begin{array}{rcl} f (\frac{- 3}{2}) & = & {(\frac{- 3}{2})}^{2} + 3 (\frac{- 3}{2}) - 10 \\ = & \frac{9}{4} - \frac{9}{2} - 10 \\ = & \frac{9 - 18 - 40}{4} \\ = & \frac{- 49}{4} \end{array}$

So, the vertex is $(\frac{- 3}{2}, \frac{- 49}{4})$ .

Step 3. Plot the Graph

Plot the parabola on a graph using the vertex and intercepts calculated in the previous step.

Step 4. Find the solution set

From the graph, it is observed that for x belonging to $(- \infty, - 5) o r (2, \infty)$ , $y > 0$ .
So, the solution set of the given inequality is $(- \infty, - 5) o r (2, \infty)$ .

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In problems 7-22, solve the inequality.
$x^{2} + 3 x - 10 > 0$

Short Answer

Step by step solution

Step 1. Given Information

Step 2. Find the intercepts and vertex

Step 3. Plot the Graph

Step 4. Find the solution set

One App. One Place for Learning.

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In problems 7-22, solve the inequality.x2+3x-10>0

Short Answer

Step by step solution

Step 1. Given Information

Step 2. Find the intercepts and vertex

Step 3. Plot the Graph

Step 4. Find the solution set

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Math Textbooks

Probability and Statistics

Pure Maths

Applied Mathematics

Geometry

Logic and Functions

Calculus

Study anywhere. Anytime. Across all devices.

In problems 7-22, solve the inequality.
$x^{2} + 3 x - 10 > 0$