Question

Number Patterns. The sequence 4;9;x;37;...is a quadratic sequence
a) calculate x
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Answer 1

@mathmate ?

Answer 2

If it is a quadratic sequence, it means that the second difference is a constant.
Can you figure out 2 second differences and equate them (hence find x)?
If you need further help, tag me.

Answer 3

@mathmate i can only get the first difference which is 5. I don't know what to do from there

Answer 4

You will need 3 first diffences to find two second differences.
The other two first differences will be in terms of x.
So are the two second differences.

Answer 5

nope, and that's my problem

Answer 6

Numbers are
4
9
x
37
The first differences are
9-4
x-9
37-x
Can you work with the second differences?

Answer 7

@mathmate i got that the difference of 9 and 4 is 5, and x=9; x=37. I really don't know how to get the second difference

Answer 8

Don't forget that x represents a number, and is part of the difference. You're missing x in your calculations.
For example, the first difference are
9-5=4
(x-9)....... and not 9.
37-x...... and not just 37.

Continue to find the second difference, both of them. They should be a constant, in terms of x.

Answer 9

@jake_litt
sorry there was a power failure. It's now back on.