Maths IGCSE
What is 0.00921 in standard form?
9.21*10^-3. REMEMBER TO PUT MINUS!!!
Line of best fit must go through which point?
(Mean x, mean y)
What are the two proofs of a cyclic quadrilateral?
1) opposite angles are supplementary (180) 2) the exterior angle is equal to the opposite interior angle
How will the graph of f(x) be different to 2f(x)? What about to the graph of f(2x)?
2f(x) will be twice as high (y-values doubled) f(2x) will be narrower
What is 6x10^10 / 3*10^5?
2x10^5, first divide 6 by 3, when take 5 away from the 10th power to get 5th power.
When you have a sequence that multiplies itself by 3 each time, what is one term in the sequence?
3^n
What is 2x10^6 X 3x10^3?
6*10^9, multiply "normal numbers" and add the tenth powers.
y = f(x) maps onto y = k*f(x) under what transformation
A VERTICAL stretch (invariant x-axis) with scale factor k
Are the bars joined together in a histogram or a column (bar) chart?
A histogram
Discrete data
Data that can be counted (2 cars)
Continuous data
Data that can be measured (1.7645 m)
Which which order would you perform transformations G,H,F and D if you saw the following as a combination of transformations FDHG
GHDF (reverse order!)
Compound interest
I = P * rate^no.of years (I=P*r^n)
Calculate the simple interest on 50,000 if there rate is 5% for 3 years
I = Prn, I = 50000 * (5 / 100) * 3
When changing a number to standard form, e.g. 14.4*10^-8, you have to move the decimal place one place to the left. How should the exponent change?
If the decimal is moving left, the exponent must move right (on the number line). In this case, the decimal is moving left, so the exponent must get bigger ('right' direction on the number line).
Helpful tip on ratios. What does the ratio 11 : 9 really mean?
If two values are in the ratio 11 : 9, it just means that one value divided by the other is equal to 11 / 9.
Simple interest, how do you get r from a percentage rate?
Interest = Principal * rate * number of years I = Prn R is percentage rate ÷ 100, e.g. a rate of 6% would have the multiplier 0.06
If there is a question on a teacher or somebody else doubting a value obtained from an equation or line of best fit, why would they doubt the value?
There is a weak correlation.
When multiplying decimals and ignoring the decimals, how many places to the left or right do you have to move the final answer? E.g. 0.35 x 4.6, you have changed to 35 * 46. You have got the answer 1610, how many decimal places must you now move the answer to the left or right, and hence what is the answer?
number of decimal places to move = total number of decimal places moved when changing decimals to whole numbers. E.g. 0.35 changed to 35, so 2 d.p.s and 4.6 changed to 46, 1 .d.p, so 3 d.p.s in total, and the answer is 1.610.
What is the formula for the period of a trigonometric graph?
Period = 360 / b, in sin(x) = sin(b*x)
If a question asks you to simplify, what should you do? If a question asks you to factorise, what should you do?
Simplify: opposite of factorisation, work forwards (multiply out brackets, divide etc.) Factorise: opposite of simplification, try to group numbers.
How to find the Interquartile Range
Split data in half and minus the middle value in second half from middle value in first half! NOT Q3 - Q1 STUFF
If in a quadratic sequence you have a second difference of 4, what will the coefficient of n^2 be? How about for a second difference of 6, and 8?
The coefficient will be 2n^2, because the coefficient is the second difference / 2. If it is the third difference, it would be third difference / 3, the fourth /4, and so on.