Posted by patricia on .
find the rules and then complete the sequence
1,2,4,3,9,5,16,7,____,____
please show workings

11+ maths 
Reiny,
if the second term has been a 1
I would see a nice pattern
the oddnumbered positions are simply the squares of the natural numbers.
i.e. the first, third, fifth, seventh ...terms are 1,4,9,16,..
then evennumbered positions are simply the odd numbers.
i.e. the second, fourth, 6th, 8th,.. terms are (1),3,5,7,...
if the second is indeed a 2 as you typed it, I see no pattern, that fits all the terms.
Once you get past the second term, the pattern I noted still applies. 
11+ maths inverse operation 
patricia,
4a + 12 = 7a  9
what is a ?
please show workings