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GCSE Maths Question.... help!

"t is a positive whole number
The expression
2t^2 + 5t + 2
can never have a value that is a prime number. Explain why"

Please help, I'm so stuck! :smile:

Reply 1

User1443542

Okay, so all odd can be written as 2t-1, and all even as 2t.

in the even case. 2(2t)^2 + 5(2t) +2 is the expression. as t cannot equal 0, the value of two is ruled out as that's the only even prime
for odds: 2(2t-1)^2 + 5(2t-1) + 2, follow through by simplifying it, and you should see the answer

Factorise?

Original post by 10hanwar

"t is a positive whole number
The expression
2t^2 + 5t + 2
can never have a value that is a prime number. Explain why"

Please help, I'm so stuck! :smile:

Because it will factorise.