# maths, proportion, formulae, sequences and inequalities

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• Created by: bio1423
• Created on: 15-06-13 17:56
• maths
• Number patterns
• Sequences
• each number is a term
• eg. Square no.s, Cube no.s, powers of 2, trisngular no.s etc.
• finding the nth term
• nth  term of a linear sequence is an+b
• a = common difference
• So, if the nth term is the first term, add in value of first term.
• e.g. 3 = 2 x 1 + b
• b = 1
• nth term is 2n + 1
• use it to find b
• Inequalities
• solved in a similar way to equations
• Dividing by a negative reverses direction of inequality
• On a number line
• solid circle means included
• hollow circle means excluded
• Graphs of inequalities
• A graph is used to find a region containing the values that satisfy an equation
• the line of the inequality is the boundary
• An excluding boundary is a dotted line
• Including boundary is solid.
• Used in linear programming
• Usd to solve allocation problems
• Formulae
• Need to be able to write a formula for given information
• Using formulae
• Describes relationship between 2 or more variables
• Must have an = in it
• Substituting into formula
• Similar to substituting into expressions
• replace letters with the values given
• work out value on calculator
• rearranging formulae
• subject of a formula is the letter on its own on one side of =
• What you do to one side, do to the other
• Collect all of subject terms that appear together
• Used when completing the square and factorisation don't work.
• x= -b+ sqrt b2 - 4ac/2a
• Proportion
• Direct Proportion
• As one increases, so does the oher
• Graph goes through the origin
• Graph is a straight line
• Inverse proportion
• When y is multiplied by a number, x is divided by that number
• graphs of y against x go to infinity when one of them Is 0.
• A curve
• Variation
• include statements such as 'd varies as the square of x'
• E.g, the value of a diamond varies directly with the square of its weight
• So, is a diamond weighing 5g is 2500, ow heavy is one worth 5000
• 1. change sentence into proportionality statement
• So, is a diamond weighing 5g is 2500, ow heavy is one worth 5000
• 2. replace proportionality symbol wit = k to make an equation. V=kw2
• 3. substitute in values in question
• rearrange to find value of k
• 5. put k value back into equation, now answer
• Proportion
• Direct Proportion
• As one increases, so does the oher
• Graph goes through the origin
• Graph is a straight line
• Inverse proportion
• When y is multiplied by a number, x is divided by that number
• graphs of y against x go to infinity when one of them Is 0.
• A curve
• Variation
• include statements such as 'd varies as the square of x'
• E.g, the value of a diamond varies directly with the square of its weight
• 1. change sentence into proportionality statement
• 2. replace proportionality symbol wit = k to make an equation. V=kw2
• 3. substitute in values in question
• rearrange to find value of k
• 5. put k value back into equation, now answer