Mathematics – Helpful Formulas

Mathematics – Helpful Formulas

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Basic Algebra

(a + b)2= a2 + 2ab + b2
(a – b)2 = a2 – 2ab + b2
a2 – b2 = (a + b)(a – b)
a2 + b2 = (a + b)2 – 2ab  or  (a – b)2 + 2ab
(a + b + c)2 = a2 + b2 + c2 + 2(ab + bc +ac)  or  a2 + b2 + c2 + 2ab + 2bc + 2ca
(a – b – c)2 = a2 + b2 + c2 – 2(ab – bc +ac)  or  a2 + b2 + c2 – 2ab + 2bc – 2ca
(a + b)3 = a3 + b3 + 3ab(a + b)  or  a3 + 3a2b + 3ab2 + b3
(a – b)3 = a3 – b3 – 3ab(a – b)  or  a3 – 3a2b + 3ab2 – b3
a3 – b3 = (a – b)(a2 + ab + b2)
a3 + b3 = (a + b)(a2 – ab + b2)
a4 – b4 = (a2 – b2)(a2 + b2)  or  (a – b)(a + b)(a2 + b2)
a5 – b5 = (a – b)(a4 + a3b + a2b2 + ab3 + b4)
an + bn = (a + b)(an-1 – an-2b + an-3b2 … – abn-2 + bn-1)

Indices

pn = p.p.p…….n times
pn⋅ pm = pm+n
pn ⋅ qn = (p ⋅ q)n
pm/ pn = xm-n
pn / qn = (p / q)n
(pn)m = pn⋅m
pnm = p(nm)
p-n = 1 / pn
a0 = 1 where a R , a!=0

 

Mathematical Properties

 

Commutative Property of Addition : a + b = b + a
Commutative Property of Multiplication : a x b = b x a
Associative Property of Addition : a + (b + c) = (a + b) + c
Associative Property of Multiplication : a x (b x c) = (a x b) x c
Additive Identity Property : a + 0 = a
Multiplicative Identity Property :  a x 1 = a
Additive Inverse Property : a + ( – a ) = 0
Multiplicative Inverse Property : a ( 1/a ) = 1
Zero Property of Multiplication  : a x 0 = 0

 

Mensuration

Perimeter
  • Square = 4a
  • Rectangle = 2a +2b
  • Triangle = a + b + c
Circumference
  • Circle = 2 (pi) r = (pi) x diameter
Area
  • Square = a2
  • Rectangle = a x b
  • Parallelogram = b x h
  • Triangle= ½ (base x height)
  • Trapezoid = h/2 (b1 + b2)
  • Circle = pi x r 2
  • Equilateral Triangle = ½(ah) = [ sqrt(3) / 4 ] x a2
  • Triangle with given a,b,c = sqrt [ s(s-a)(s-b)(s-c) ] when s = (a+b+c)/2 (Heron’s Formula)
  • Sphere = 4 (pi) r2
Surface Area
  • Cube= 6a2
  • Cylinder = 2 . pi . r . h
  • Sphere = 4 x pi x r 2
Volume
  • Cylinder = bh
  • Cone = bh/3
  • Sphere = 4 x pi x r3 / 3
Pythagoras Theorem
  • a2 + b2 = c2
Distance Formula
  • d = sqrt[(x2 – x1)2 +(y2 – y1)2]
Slope of a line
  • m = y2 – y1 / x2 -x1
Mid- Point Formula
  • M = (x1 + x2 )/ 2 , (y1 + y2 )/ 2
Slope-intercept form of the equation of a line
  • y = mx + c
Quadratic formula
  • X = [-b ± sqrt(b2 – 4ac)] /2a
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