If x^2+2=3^2/3+3^-2/3 then prove that 3x^3+9x-8=0

Question

Mathematics

Leyla Nguyen

30 January, 12:02

If x^2+2=3^2/3+3^-2/3 then prove that 3x^3+9x-8=0

+3

Answers (2)

Know the Answer?

Kason Logan · Answer 1

here is the solution

Rory Hickman · Answer 2

See below.

Step-by-step explanation:

x^2 + 2 = 3^2/3 + 3^-2/3

x^2 = 3^2/3 + 3^-2/3 - 2

x = √ (3^2/3 + 3^-2/3 - 2)

x = 0.748888296

Substitute for x in 3x^3 + 9x - 8:

3 (0.748888296) ^3 + 9 (0.748888296) - 8 = 0.

So it is proved.