Fiszki: maths formulas paper 1 | Quizlet

diff of cubes

(x³- y³) = (x - y)(x² + xy + y²)

sum of cubes

x³ + y³ = (x + y)(x² - xy + y²)

real roots

b²-4ac≥0

equal roots

b² - 4ac = 0

no real roots

b²-4ac<0

factor theorem

if x-k is a factor of f(x) then x=k is a root

modulus of complex no

square root of x² + y²

commutative

a + b = b + a

associative

(a+b)+c=a+(b+c)

distributive

a(b+c)=ab+ac

error

accurate-observed

relative error

error divided by accurate value

percentage error

error divided by accurate x 100

arithmetic sequence difference

d = T3 - T2 = T2 - T1

arithmetic sequence sum

Tn = Sn - Sn-1

quadratic sequence general term

an²+bn+c
2nd difference 2a

% profit, mark up

profit/loss divided by cost price x 100

% profit, margin

profit divided by selling price x 100

gross tax

standard tax + higher tax.

tax payable

gross tax - tax credit

net income

gross income - tax payable