Posted by **Anonymous** on Monday, September 16, 2013 at 11:51pm.

(4x)^2/3=(30x+4)^1/3

please explain=)

- math -
**Jai**, Tuesday, September 17, 2013 at 12:21am
(4x)^(2/3) = (30x+4)^(1/3)

To do this, note that it's much easier to work with whole number exponents. This we raise both side terms by 3, so that the denominator 3 will be cancelled:

(4x)^(2/3 * 3) = (30x+4)^(1/3 * 3)

(4x)^2 = (30x+4)^1

16x^2 = 30x + 4

Solving for x,

8x^2 - 15x - 2 = 0

(8x + 1)(x - 2) = 0

x = 2

x = -1/8

Then we check by substituting these x values to the original equation:

i. x = 2

(4x)^(2/3) = (30x+4)^(1/3)

(4*2)^(2/3) = (30*2+4)^(1/3)

(8)^(2/3) = 64^(1/3)

2^2 = 4

4 = 4

Thus x is indeed equal to 2.

ii. x = -1/8

(4x)^(2/3) = (30x+4)^(1/3)

(4*(-1/8))^(2/3) = (30*(-1/8)+4)^(1/3)

(-1/2)^(2/3) = (-15/4 + 16/4)^(1/3)

(1/4)^(1/3) = (1/4)^(1/3)

Thus x is also equal to -1/8.

Hope this helps~ :3

- math -
**sara**, Wednesday, September 18, 2013 at 2:05am
i didn't get how 16x^2 turned into 8x^2

16x^2 = 30x + 4

Solving for x,

8x^2 - 15x - 2 = 0

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