Solve this quadratic equation by completing the square. x^2 + 6x = 18

Question

asked Nov 25, 2022 191k views

1 Answer

Dbrane · Answer 1 · 2022-11-30T21:22:46+0000

Explanation:

Use formula

$((b)/(2) ) {}^(2)$

To add a third new term and factor to find the answer. Example

$x {}^(2) + 6x = 18$

$( (6)/(2) ) {}^(2)$

Which equal 9. so our equation look like

${x}^(2) + 6x + 9 = 18 + 9$

The only number that multiply to 9 and add up to 6 is 3. So we write our equation like this.

$(x + 3) {}^(2) = 27$

Take the sqr root of both sides

Subtract 3 from both sides

Since a sqr root of a number can be positive or negative, the answer is

or