Question

0/1 Solve the equation by completing the square. Round your answer to the nearest hundredth, if necessary x^2+18x=7

Answer 1

The solution to the equation is x = 0.38 or -18.38

Explanation:

x^2+18x=7 can be properly written as

`x^(2) +18x =7`

To solve by completing the square, divide the coefficient of x by 2, square and then add to both sides

i.e 18/2 = 9

Then add 9² to both sides of the equation

`x^(2) +18x + 9^(2) = 7 + 9^(2)`

This becomes

`(x+9)^(2) = 7 + 81`

`(x+9)^(2) = 88`

`x+9 = \pm √(88)`

`x = -9 \pm√(88)`

`x = -9 \pm 9.38`

∴
`x = -9+9.38 or -9-9.38`

`x = 0.38 or -18.38`

Hence, x = 0.38 or -18.38