liemluji
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Hi
I was revising the first topic on Further Pure 1 which is roots of a quadratic equation with alpha and beta. I came across a question where I got the answer but somehow doesn't match the answer to the back of the book.

Q) The roots of the quadratic equation x^2+3x-2=0 are alpha and beta.

without solving the equation, find the value of:
a)1/alpha^2 + 1/beta^2

i got 3 as an answer but apparently it's 7/4.

please let me know if my asnwer is wrong thanks!
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jacksir1235
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Hello if you having a bad day check this funny video
https://www.youtube.com/watch?v=8a9j4hUxqck
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ludmila
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(Original post by liemluji)
Hi
I was revising the first topic on Further Pure 1 which is roots of a quadratic equation with alpha and beta. I came across a question where I got the answer but somehow doesn't match the answer to the back of the book.

Q) The roots of the quadratic equation x^2+3x-2=0 are alpha and beta.

without solving the equation, find the value of:
a)1/alpha^2 + 1/beta^2

i got 3 as an answer but apparently it's 7/4.

please let me know if my asnwer is wrong thanks!
I got 13/4.
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(Original post by liemluji)
Hi
I was revising the first topic on Further Pure 1 which is roots of a quadratic equation with alpha and beta. I came across a question where I got the answer but somehow doesn't match the answer to the back of the book.

Q) The roots of the quadratic equation x^2+3x-2=0 are alpha and beta.

without solving the equation, find the value of:
a)1/alpha^2 + 1/beta^2

i got 3 as an answer but apparently it's 7/4.

please let me know if my asnwer is wrong thanks!
 \frac{1}{\alpha^2} + \frac{1}{\beta^2} = \frac{\alpha^2 + \beta^2}{\alpha^2 \beta^2}

Does that make it any easier?


EDIT: In line with what ludmilla has said above, 7/4 is incorrect. But so is 3.
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