Chapter 9: Q. 102 E (page 885)

In the following exercises, solve by completing the square.
$5 x^{2} + 20 x = 15$

Short Answer

Expert verified

The solution is $x = - 2 - \sqrt{7}, x = - 2 + \sqrt{7}$

Step by step solution

Step 1. Given information

Equation: $5 x^{2} + 20 x = 15$

Step 2. Calculation

We have,

$5 x^{2} + 20 x = 15$

$5 (x^{2} + 4 x) = 5 (3)$

$\frac{5 (x^{2} + 4 x)}{5} = \frac{5 (3)}{5}$

$x^{2} + 4 x = 3$

$x^{2} + 4 x + {(\frac{1}{2} \cdot (4))}^{2} = 3 + {(\frac{1}{2} \cdot (4))}^{2}$

$x^{2} + 4 x + {(2)}^{2} = 3 + {(2)}^{2}$

$x^{2} + 4 x + 4 = 3 + 4$

${(x + 2)}^{2} = 7$

$\sqrt{{(x + 2)}^{2}} = \sqrt{7}$

$x + 2 = \pm \sqrt{7}$

$x + 2 - 2 = - 2 - \sqrt{7}, x + 2 - 2 = - 2 + \sqrt{7}$

$x = - 2 - \sqrt{7}, x = - 2 + \sqrt{7}$

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In the following exercises, solve by completing the square.
$5 x^{2} + 20 x = 15$

Short Answer

Step by step solution

Step 1. Given information

Step 2. Calculation

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In the following exercises, solve by completing the square.5x2+20x=15

Short Answer

Step by step solution

Step 1. Given information

Step 2. Calculation

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Math Textbooks

Mechanics Maths

Probability and Statistics

Decision Maths

Statistics

Logic and Functions

Discrete Mathematics

Study anywhere. Anytime. Across all devices.

In the following exercises, solve by completing the square.
$5 x^{2} + 20 x = 15$