Chapter 9, Problem 46SGR

To determine

To compute the value of the equation using quadratic formula.

Answer to Problem 46SGR

The value of x is -2 and 10.

Explanation of Solution

Given information :

The function provided is $x^2-8x=20$ . This can be written as $x^2-8x-20=0$ .

Formula used :

Quadratic formula is $x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$ . Here ‘a’, ‘b’ and ‘c’ are the co-efficient of the given equation.

Here, $a=1,b=-8\text{ and}c=-20$ .

Calculation :

  $x=\frac{-(-8)\pm \sqrt{{(-8)}^2-4\times (1)\times (-20)}}{2(1)}$

Putting the values in the formula.

  $x=\frac{8\pm \sqrt{64+80}}{2}$

Simplifying

  $x=\frac{8\pm \sqrt{144}}{2}$

Removing square root.

  $x=\frac{8\pm 12}{2}$

One of the roots is

  $x=10$

This is the first root.

Second root is.

  $x=-2$