MaxWong

pi is the ratio between the circumference of a circle and the diameter of the SAME circle.

And I think that wasn't calculus and it is statistics instead??

False.

$\left(\dfrac{5}{9}\right)^2\\ =\dfrac{5^2}{9^2}\leftarrow\boxed{\left(\dfrac{a}{b}\right)^m=\dfrac{a^m}{b^m}}\\ =\dfrac{25}{81}$

Do something / something.

Divisions = Fractions.

$y = 1-\dfrac{\sec x}{\tan x} =1 - \sec x \cot x = 1- \dfrac{1}{\cos x \tan x}=1-\dfrac{1}{\sin x}\\ y'=(1-\dfrac{1}{\sin x})'=0-(\dfrac{\cos x}{\sin^2x})=-\dfrac{\cos x}{\sin^2x}$

You can think about it like this:

754 - 175.5 = 754 - 175 - 0.5 = 579 - 0.5 = 578.5 :)

2(x) + 2(2)= 2(x+2)

Q:Why x<-1 or x>1 is not correct?

A; Try substituting any number in the range x<-1 or x>1 into the original inequation (x^2 <1), that doesn't fit in the original inequation. You will get something like 3<1 or 1>4.

-2x + 13 = 7

        -2x = -6

           x = 3