Hello from MrBillDoesMath
Answer: -4x^3 + 8x^2 -5x + 12
Discussion:
Standard for for a polynomial meas tne power of x descend so standard fro of
8x^2 - 4x^3 +12 -5x is
-4x^3 + 8x^2 -5x + 12
Note: the problem statements shows this ":8x^2". I didn't know how to deal with the ":" character so simply ignored it.
Thank you,
Mr. B
Answer:
The easiest approach is to realise that one hour is 3 times longer than 20 minutes. The longer the time, the more they will pave.
215 of a mile, in 20 minutes, how much in 60 minutes?#
They will pave 3 times more.
215×31=615 of a mile
615=25 of a mile
You could also use the 'unitary method' where you find out how much they pave in ONE minute (divide by 20) and them multiply by 60 to find how much in one hour.
Look at what happens:
215÷20×60
=215×120×603
=215×3 ← exactly the same maths.
=25
The tan(-x) is the same thing as -tan(x). The tangent function is also the same thing as sin(x)/cos(x), right? So let's rewrite that tan in terms of sin and cos:
![[cos(x)][tan(-x)]](https://tex.z-dn.net/?f=%5Bcos%28x%29%5D%5Btan%28-x%29%5D)
is the same as
![[cos(x)][ -\frac{sin(x)}{cos(x)}]](https://tex.z-dn.net/?f=%5Bcos%28x%29%5D%5B%20-%5Cfrac%7Bsin%28x%29%7D%7Bcos%28x%29%7D%5D%20)
We can now cancel out the cos(x), which leaves us only with -sin(x) remaining. So your answer is A.