D is a notation for differential. There is a d2 in your formula because in the numerator there are two differentials. The formula is thus the second derivative of a function with respect to two variables.
Answer: D
1/2x-1+4=x
1/2x-x=-3
-1/2x=-3
x=6
If a pentagon is regular, then all of the sides are the same length. This means that
So, if 
, the lengths of the sides evaluate to
So, all the sides of the pentagon are 21 units long, and AB is 21 units long as well, because all sides are the same length.
In one hour he traced the distance of: 36.15 miles
With one gallon of gas he went: 12.05 miles
;) There you go! Good Luck!
1. <span>-0.9x+2.8=4.1
First subtract 2.8 from both sides.
-0.9x = 1.3
Now divide both sides by -0.9.
x = -1.4444..
This can be rounded to -1.44
</span><span>c) -1.44
2. Jordan has 650 pennies. He'll give 85 to his brother and split the rest with his sister.
</span>d) 85+2x=650
