Question

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

x = 3 plus-or-minus StartRoot 23 EndRoot
x = 3 plus-or-minus StartRoot 51 EndRoot
x = 3 plus-or-minus StartRoot 41 EndRoot
x = 3 plus-or-minus StartRoot 5 EndRoot

Answer 1

a

Explanation:

Answer 2

first option

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 = ±
`√(23)` ( add 3 to both sides )

x = 3 ±
`√(23)`