Question

Solve for x in the equation 3 x squared minus 18 x + 5 = 47.

Answer 1

Answer:

first option

Step-by-step explanation:

3x² - 18x + 5 = 47 ( subtract 5 from both sides )

3x² - 18x = 42 ( divide through by 3 )

x² - 6x = 14

Using the method of completing the square

add ( half the coefficient of the x- term )² to both sides

x² + 2(- 3)x + 9 = 14 + 9

(x - 3)² = 23 ( take square root of both sides )

x - 3 = ± $\sqrt{23}$ ( add 3 to both sides )

x = 3 ± $\sqrt{23}$