Question

Which of the following values of x satisfy the equation 3x^2 - 8x + 4 = 0 ?

A. x=2 and x=2/3
b. x=4 and x=1/3
c. x= -2 and x=-2/3
d. x= -4 and x= -1/3

Answer 1

3x^2 - 8x + 4 = 0

3x^2 - 6x - 2x + 4 = 0
3x(x - 2) - 2(x - 2) = 0
(3x - 2)(x - 2) = 0

x = 2/3 and x = 2

Its A

Answer 2

You can do it in two ways:

1) solve the equation

2) replace the values given in the equation.

To solve the equation you can use the quadratic formula,

x = (- b +/- √[b^2 - 4ac] / (2a)

=> x = { - (-8) +/- √ [ (8^2) - 4(3)(4) ] } / (2*3) = { 8 +/- √ [64 - 48] } (6)

x = { 8+/- √16 } / (6) = { 8 +/- 4 } / 6

x = (8+4) / 6 and x = (8 - 4)/ 6

x - 12 / 6 and x = 4 / 6

x = 2 and x = 2/3

Answer: option A. x = 2 and x = 2/3