Paper 2 Logic Flashcards
(94 cards)
why must you always check before taking the logarithm of both sides?
- taking logs can loose/ add solutions
- Always make domain resitricts as to check that the value is positive ( cannot be = 0 either)
Loging and squaring can both introduce extra solutions. The substitution trick is neat
Necessary but not sufficient means you can deduce the outcome from what you are given. BUT you canβt go the other way round (outcome to condition)
If a part of the inequality is true for all values of x, you can drop the inequality
Simple notation
For a sufficient condition to be true, must be affirmative (100%) no maybes
Recognise that recurring means sum to infinity
What is 2nd approach to this question
They always want you to think in term of geometric series sums
What can you infer about stationary points given the number of roots?
Number of stationary points = at least (number of roots -1) between every root.
BUT may also be more stationary points between these pairs of values or before the first or after the last value. eg
Might be more efficient to have a yes no prime section to avoid misses
what is the simplest way to rationalise surd?
What does this mean?
What is a way to view the modulus function
The positive distance of x from 3
Draw the graph of
(One to one function)
Bear in mind. It is just assumed the input values will always be positive and zero. Also when they give square root it is also just assumed it is the positive square root.