maths formule

we got a wordsheet that consists many useful formule. all formule are common but being together, makes really easy to revise.
first page i am posting right now.


GMAT FORMULAS
Summation Formula = (Number of numbers)/2 * (f + l), where number of numbers = f – l + 1

Percent Change = Difference/Original

Rectangular Solid Volume = L*W*H

Cube Volume = S*S*S

Cylinder Volume = PieRsquaredH

Surface Area (Combined area of all the surfaces, or faces, of a solid)

Surface Area of Rectangular Solid = 2lw + 2lh + 2wh

Surface Area of a Cube = 6ssquared

Principal + Interest = principal * (1+r)>t, where

Total = Group 1 + Group 2 – Both + Neither

Quadratics
• (x + y)2 = x2 + 2xy + y2
• (x – y)2 = x2 – 2xy + y2
• (x + y)(x – y) = x2 – y2

Number of permutations (different arrangements when order matters) = (n!)/(n-r)!

Number of combinations (arrangements when order doesn’t matter) = (n!)/r!(n-r)!

where n = number of objects in the source group
where r = number of objects selected

The length of a given side must be greater than the difference of the other two sides and less tha
the sum of the other two sides.