# All Questions

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### Find all positive integers that solve Mordell's equation $y^2=x^3+37$

Find all Mordell's equation: $$y^2=x^3+k$$ where $k=37$ positive integer numbers,I can't find the when $k=37$ the mordell equation solution with some result,and we can known this equation have ...
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### An extemal combinatorial design question. “Weak” steiner stystems.

A Steiner system $S(t,k,\nu)$ is a collection $X$ of $\nu$ points and a collection of subsets of $X$ of size $k$ (frequently called blocks) such that each $t$ element subset of $X$ occurs in exactly ...
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### Prove this diophantine equation $2^a-3^b=5~，a,b\in N^{+}$ has no postive integers solution

show that the diophantine equation $$2^a-3^b=5~~~~,a>5,b>3，a,b\in N^{+}$$ has no postive integers solution maybe is old problem,But I try somedays,can't solve it by now
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### Parameters leading to an elementary integral

For which values of $a,b$ the following integral is an elementary function, and which elementary function? $$\int \frac{x^2+ax+b}{(x-1)^2}\,e^x\, dx$$ I tried to solve this integral but it ...