Algebra II review help!?

Question

I'm in pre calc, and we're reviewing algebra II right now. I'm having trouble with a wksht problem (factoring):
R ^(2/3) - R ^(1/3) - 20 = 0

please don't just give me the answer! give me a little explanation. thanks!

Answer 1

The square root of R^(2/3) can be found by taking half the power, so it is R^(1/3). Factors of -20 that add up to -1 are -5 and +4.

So factoring we get:

(R^(1/3) -5)(R^(1/3)+4)=0

So R^(1/3) = -5 or R^(1/3) = 4


I just saw my mistake! Use the answer below mine!

Cube both sides of each eqn to get
R = -125 or R = 64

Answer 2

A. The locomotive and cabin vehicle are mounted. the relax 7 vehicles could be permuted in 7! = 50450 procedures. B. 3, 7, 11, 15... it incredibly is an mathematics sequence with initiate 3 and distinction 4 so as that the nth term is 3 + (n-one million)4 which equals 3 -4 + n(4) = 4n-one million seventy 8. say the threat that Jamie tries out for baseball is x. Then she would be ready to attempt for basketball with prob. one million-x. So the possibility that she would be ready to attempt for catcher is .7x = .40 two subsequently x = .6 subsequently one million-x = .4

Answer 3

Its a simple equation which needs resolving. Ist add 20 to both sides to get

R ^(2/3) - R ^(1/3) =20

now you can see that the left side can be simplified

If you know how to add and subtract powers, you should be able to figure out

R^(something goes here, not telling you what)=20

from there you can find R

Answer 4

try this...

Let x = R^(1/3) then the eq is

x^2 - x - 20 = 0
(x - 5)(x+4) = 0
so x = 5 or x = -4

so R^(1/3) = 5 R = 125
R^(1/3) = -4 R = -64