Important tips before walking into the exam!! Three significant figures when appropriate!!
- comparing cumulative frequency graphs: more/similar spread (indicated from interquartile range), higher/lower median
- sketch a graph when asked to solve inequalities
- if range does not indicate domain, means the whole graph, therefore only above the asymptote
- in graph questions, leave answers in decimals 3 s.f
- use sine rule for area even if it’s right triangle
- transformation of inverse graph: ALWAYS includes reflection
- when ask to write down an expression, no need to simplify e.g. 0.5•10•10•sin x
- if question asks to show that … =30m, correct to 1 decimal place. show at least 4 figures in method before rounding it to 1 decimal place
- (±)after squares e.g. x^2=25, x=±5
- if the answer is ±5, write 5, -5
- don’t leave answer in standard form unless stated otherwise
- if the numbers in the question are in standard form, then write answers in standard form
- Linear regression: round m and b to 3 significant figures
- add one step with one value e.g. mx+b, 3x+b
- Describing patterns: large samples, no correlation…
- If question refers to f(x), don’t use y
- substitute number in for π r^2 before simplifying anything
- answer questions according to the number of marks (especially describing patterns)
- SHOW WORKING IF QUESTION IS MORE THAN 1 MARK
- leave denominator in surds form and factorized polynomials
- IQR: numbers are in between, if even number e.g. 60th, average between 60-61,
- round it e.g. upper quartile of 10 is 7.5, round it to 8
- use the calculator value (degree of accuracy) even when it’s rounded or 3 s.f.
- give one step of working for factorizing polynomials e.g. (x+a)(7x+b), ab=16
- Rotational symmetry order ? about (x,y) (center point)
- Stretch factor: multiply points by stretch factor
- x-axis invariant means don’t stretch the x value
- enlargement by a stretch factor of -2 about (0,1) means first rotate 180˚
- discrete data e.g. number of students, continuous data e.g. heights
- modal interval: the interval with the most frequency
- frequency density = frequency/class width (watch out for the range 0≤x≤30 or 0<x≤30)
- double check all work INCLUDING the ones relying on calculators
- check everything with at least two methods e.g. graphing + algebra
IGCSE REVISION 