# AQA Maths Notes (complete)

- Created by: Skye Galpeer-Shade
- Created on: 18-06-13 21:54

First 189 words of the document:

Maths Unit 3

Solving equations with graphs: The solution is always where the two graphs cross use it to solve

simultaneous equations

Quadratic formula:

ax^2+bx+c = 0

X= (-b +/- sqrt (b^2 - 4ac)) / 2a

E.g 3x^2 +7x =1

3x^2+ 7x 1 = 0

A= 3 b=7 c=-1

(-7 +/- sqrt (49 +12)) / 6

(-7 +/- 7.81) / 6

= -14.81 / 6

OR

= 0.81 / 6

If it says proportional it means multiply

Inversely proportional to means divide

E.g y is proportional to the square of x = y = kx^2

d varies with the cube of t = d=kt^3

t is proportional to the square root of h = t= k sqrt h

v is inversely proportional to r^3 = v=k/r^3

The time (t) taken for a duck to fall down a chimney is proportional to the square of the diameter (d)

of the chimney

T=kd^2

If she took 25secs to descend a chimney with a diameter of 0.3m how long would it take her to fall

down a 0.2 diameter?

25 = k * 0.09

K = 25/0.09 = 278

T= 278 * 0.2^2 = 11.12secs

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