Chapter 6: Q. 427 (page 636)

Solve Quadratic Equations by Factoring in following exercises, solve.
$x^{2} + 9 x + 20 = 0$

Short Answer

Expert verified

The solutions of the given expression are $x = - 4 a n d - 5$ .

Step by step solution

Step 1. Given and explanation

We have $x^{2} + 9 x + 20$ .

We will first simplify the equation by factorizing.

We will then every factor equal to zero according to the zero product property to find the values.

Step 2. Simplifying the equation by factorizing.

We have $x^{2} + 9 x + 20$ .

We can write this as $x^{2} + 4 x + 5 x + 20$ .

Simplifying it,

$= x^{2} + 4 x + 5 x + 20 = x (x + 4) + 5 (x + 4) = (x + 4) (x + 5)$

Step 3. Finding values.

We now have $(x + 4) (x + 5) = 0$ .

Putting each factor equal to zero gives us,

$x + 4 = 0 x = - 4$
$x + 5 = 0 x = - 5$

This shows that values are $- 4 a n d - 5$ .

Step 4. Check the solution.

We will check the solution by putting the value of the solution in the equation separately. If the equation satisfies, our answer is right.

When $x = - 4$
${(- 4)}^{2} + 9 (- 4) + 20 = 0 16 - 36 + 20 = 0 36 - 36 = 0 0 = 0$
Hence satisfied.
When $x = - 5$
${(- 5)}^{2} + 9 (- 5) + 20 = 0 25 - 45 + 20 = 0 45 - 45 = 0 0 = 0$
Hence satisfied.

Thus our calculations are right.

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Solve Quadratic Equations by Factoring in following exercises, solve.
$x^{2} + 9 x + 20 = 0$

Short Answer

Step by step solution

Step 1. Given and explanation

Step 2. Simplifying the equation by factorizing.

Step 3. Finding values.

Step 4. Check the solution.

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Solve Quadratic Equations by Factoring in following exercises, solve.x2+9x+20=0

Short Answer

Step by step solution

Step 1. Given and explanation

Step 2. Simplifying the equation by factorizing.

Step 3. Finding values.

Step 4. Check the solution.

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Math Textbooks

Theoretical and Mathematical Physics

Statistics

Discrete Mathematics

Mechanics Maths

Geometry

Pure Maths

Study anywhere. Anytime. Across all devices.

Solve Quadratic Equations by Factoring in following exercises, solve.
$x^{2} + 9 x + 20 = 0$