Mathematical induction
i)
You need to know summation, ∑ before you learn it.
In a summation sign, you will see several numbers.
The number below the sign is where you start counting, the number above is
where you stop, and you substitute the number to the algebra in the right of
the sign. So, in this case it would be 1+2+3+4.
In this case, we start from 1 to 3, and substitute it into (2i+5)
The answer would be (2*1+5) +(2*2+5) +(2*3+5) =7+9+11=27
Sometimes, we the summation sign would not be calculate-able, for example
when the number in the bottom is larger than the number in the top. Or when
there are decimals.
If the algebra isn’t there, we can just ignore it and do simple addition.
And if you see multiplication, you can take the number out.
Application of mathematical induction: prove formulae