Help simplifying this algebraic expression please

[homeworkhelpls]

14) here i tried 3x^3 + 3/8x^3 to to get 27/8x^3 but the answer is 3/2 x^3, why?

15) here i did 9x^3/2 - 1/x^3/2 to get 9x^9/4 - 1/x^3/2 but that's not in the right form, how do i do it correctly?

 

[FactChecker]

View attachment 31519414) here i tried 3x^3 + 3/8x^3 to to get 27/8x^3 but the answer is 3/2 x^3, why?

Did you take the cube root of the constant multiplier?

View attachment 31519615) here i did 9x^3/2 - 1/x^3/2 to get 9x^9/4 - 1/x^3/2 but that's not in the right form, how do i do it correctly?

That is not correct. You can not simply square the individual terms. Do you know what the general result of $(a-b)^2$ is? Multiply out the square to see what is right.

 

[homeworkhelpls]

ok then for 15 i expanded the brackets and got 9x^3/2 -3x^0 - 3x^0 + x^-3/2, I am confused if -3x^0 is equal to -3 or 1, please explain

 

[homeworkhelpls]

Did you take the cube root of the constant multiplier?

That is not correct. You can not simply square the individual terms. Do you know what the general result of $(a-b)^2$ is? Multiply out the square to see what is right.

and for 14 i got it now after doing 3 x by cubed root of 3 x by x^3 all over 2 to get 3/2 x^3, thanks :)

 

[FactChecker]

ok then for 15 i expanded the brackets and got 9x^3/2 -3x^0 - 3x^0 + x^-3/2, I am confused if -3x^0 is equal to -3 or 1, please explain

A product of both. $-3x^0 = -3 \cdot x^0 = -3 \cdot 1 = -3$