Honestly I would recommend you watch an online video on it.
But think of it this way,
Combinations is used when you "Choose" a certain number of things out of a total number and order does not matter.
Permutations are when you permutate or arrange in a "Particular" order where order matters.
Answer:
-7/2
Step-by-step explanation:
y2-y1 / x2-x1
-5-10 / -2-4
-15 / -6
-7 / -2
= -7/2
Answer:
-0.05
Step-by-step explanation:
This will become much easier if we can get the ugly decimal into a nice fraction form.
Start by recognising 
. This is almost correct except the fraction is out by some number of factors of 10 (because the 125 part is correct but the number of 0s isn't).
And hence we see that 
and now the cube root becomes easy to compute:
![\sqrt[3]{-0.000125} = \sqrt[3]{\frac{-1}{8000}} = \frac{\sqrt[3]{-1}}{\sqrt[3]{8000}} = \frac{-1}{20} = -0.05](https://tex.z-dn.net/?f=%5Csqrt%5B3%5D%7B-0.000125%7D%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B-1%7D%7B8000%7D%7D%20%3D%20%5Cfrac%7B%5Csqrt%5B3%5D%7B-1%7D%7D%7B%5Csqrt%5B3%5D%7B8000%7D%7D%20%3D%20%5Cfrac%7B-1%7D%7B20%7D%20%3D%20-0.05)
.
Advanced: You ask for <em>all </em>real cube roots. however the function ![y=\sqrt[3]{x}](https://tex.z-dn.net/?f=y%3D%5Csqrt%5B3%5D%7Bx%7D)
is described as <em>bijective</em>. This means for all x, there is only one y corresponding to it. (And also for all y there is only one x corresponding to that). This means there can only ever be one cube root of any real number.
