5
Dec
2020
Question of the Day By Maths Grinds
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For what values of rational $p$ and $q$ will $p\sqrt{2}+q\sqrt[3]{3}$ be rational? You may assume $\sqrt[3]{3}$ is irrational and of course $\sqrt{2}$ is irrational too. Recall though that the sum of two irrationals can be either rational or irrational. Hint: remember how to compare surds.
4
Dec
2020
Question of the Day By Maths Grinds
Calculate $ \lim\limits_{n \to \infty } \sum \limits_{k=1}^n 4^{-k} $.
3
Dec
2020
Question of the Day By Maths Grinds
Calculate the limit $ \lim\limits_{n \to \infty } \frac{\left(n^2+3\right)^\frac{1}{2}}{\left(n^2+2\right)^\frac{1}{3}} $.
2
Dec
2020
Question of the Day By Maths Grinds
Calculate the limit $ \lim\limits_{n \to \infty } \cos \frac{1}{\sqrt{n}}} $.
1
Dec
2020
Question of the Day By Maths Grinds
For what values of $x$ will the following converge absolutely? $\sum\limits_{n=1}^\infty \frac{\left(3x-2\right)^n}{n}$
30
Nov
2020
Question of the Day By Maths Grinds
For what values of $x$ will the following converge absolutely? $\sum\limits_{n=1}^\infty n! x^n$
29
Nov
2020
Question of the Day By Maths Grinds
For what values of $x$ will the following converge absolutely? $\sum\limits_{n=1}^\infty 3^n \frac{ x^n }{ n! } $
28
Nov
2020
Question of the Day By Maths Grinds
For what values of $x$ will the following converge absolutely? $\sum\limits_{n=1}^\infty \left(-1\right)^{n-1} \frac{ x^n }{ n } $
27
Nov
2020
Question of the Day By Maths Grinds
Given that $0 < a < b$ prove $a < \sqrt{ab} < b$ and $ \sqrt{ab} < \frac{a+b}{2}$
26
Nov
2020
Question of the Day By Maths Grinds
Prove by induction that $1^3 + 2^3 + \cdots + k^3 = \left(1+2+\cdots+k\right)^2$.