MaxWong

LOL I have Pikachu in game though.

The formula for standard deviation is :

Let there are n numbers in a set x and the mean of the set is $\mu$Moooooo XDD

 $\sigma=\sqrt{\dfrac{(x_1-\mu)^2+(x_2-\mu)^2+......+(x_n-\mu)^2}{n}}$

Division is same as fractions.

:D

Let x be the airplane speed and y be the wind speed.

Because distance/time = speed......

$x+y=\dfrac{2500}{3.75}$

$x-y=\dfrac{2500}{4.4}$

Add up the 2 equations:

 $2x=\dfrac{2500}{3.75}+\dfrac{2500}{4.4}=1234\dfrac{84}{99}\\ x = 617\dfrac{4}{9}\text{miles/h}$

$617\dfrac{4}{9}+y=\dfrac{2500}{3.75}\\ \dfrac{5557}{9}+y=\dfrac{2000}{3}\\ y = \dfrac{6000}{9}-\dfrac{5557}{9}=49\dfrac{2}{9}\text{miles/h}$

$\;\;\;\;\;.\\0.46$

$\;\qquad\;\;\;\;\;\;\;\;\;\;.\\=0.4 + 0.06$

$=\dfrac{2}{5}+\dfrac{\frac{2}{3}}{10}\\ =\dfrac{12}{30}+\dfrac{2}{30}\\ =\dfrac{14}{30}\\ = \dfrac{7}{15}$

In the absolute values bracket, everything become positive :D (Stays positive :DDDD)

|$\begin{array}{c}\circ\\↑\\\text{^}\\\end{array}$|<-- That man was positive LOL.

|-1 2/5| = 1 2/5

-|-1 2/5| = -(1 2/5) = -1 2/5

-1 2/5 = -7/5 (division)= -1.4

Same as geno's answer

Do you mean $9^2-\dfrac{3^3}{2^4+11}$?

$9^2-\dfrac{3^3}{2^4+11}\\ = 81-\dfrac{27}{16+11}\\ =81-\dfrac{27}{27}\\ = 80$

Definitely a funny question. Such a complicated expression can give a simple answer. :D

Therefore it takes 6 hours to hike 12 miles.

First question:

$\sqrt2 - \sqrt 3\\ = \dfrac{2-3}{\sqrt2+\sqrt3}\\ = -\dfrac{1}{\sqrt2 + \sqrt 3}\\ \text{I think your teacher wants you to do this.}$

Second question:

$(3\sqrt5-2\sqrt3)(3\sqrt5-2\sqrt3)\\ = 45 - 12\sqrt{15}+12\\ = 57-12\sqrt{15}$

Third: Greatest = 6sqrt7, Least = sqrt7

Reason: It is because sqrt7 is a positive number. If you use a greater positive number to multiply it, the product would be greater. Therefore 6sqrt7 is the greatest and sqrt7 is the least.