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Show that if a polynomial with integer coefficients has a rational root, then the rational root must be an integer. Hence, show that x^n-5x+7=0 has no rational roots.

Let f(x)=x^n+a_(n-1)x^(n-1)+...+a_0 with n>=2 and a_i an integer have a rational root x=p/q.

Consider q^(n-1)f(p/q).

q^(n-1)f(p/q)=p^n/q+a_(n-1)p^(n-1)+...+a_0q^(n-1)=0

==> a_(n...

PA
Answered by Peter A. STEP tutor
5391 Views

How to differentiate tan(x)?

tanx = sinx/cosx. Express this as: sinx*(cosx)^-1. Remembering the product rule: "y = f(x)g(x), dy/dx = f'(x)g(x) + f(x)g'(x)". sinx differentiates to cosx and cosx differentiates to -sinx. Also...

KA
Answered by Kai A. Maths tutor
10641 Views

How do I tackle the personal statement?

Writing a personal statement for any course is a daunting task and when the course you're applying for has a 10 people applying for every 1 place, it can at times seem impossible. As a current medical stu...

JM
2349 Views

What is the geometry of a ClF3 molecule? (AQA Unit 1 2015 1d)

Chlorine, Cl, and Florine, F are both in group 7 of the periodic table so they have 7 electrons in the outer energy level, called valence electrons. Each fluorine atom makes one covalent bond to the chlor...

EC
Answered by Eleanor C. Chemistry tutor
13176 Views

How to complete the square?

This is a handy trick for quadratic equations ax^2 + bx + c = 0.

e.g. (x^2 + 5x + 6). So a = 1, b = 5 and c = 6.

To complete the square, let x^2 + 5x + 6 = 0. Then, take 6 to the other side ...

JP
Answered by Jigar P. Maths tutor
4162 Views

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