Question

Ajutati-ma si pe mine la aceste probleme.

a) x+2x+3x+...+20x
b)$\frac{x+1}{1ori3}+ \frac{x+1}{3ori5}+ \frac{x+1}{5ori7}+....+ \frac{x+1}{2009ori2011}= \frac{1005}{2011}$ acolo unde este ori este inmultire.
c)$\frac{x}{ \sqrt{2}+1 } + \frac{x}{ \sqrt{3}+ \sqrt{2} }+ \frac{x}{ \sqrt{4}+ \sqrt{3} }+....+ \frac{x}{ \sqrt{2025}+ \sqrt{2024} }=4004$

Answer 1

a)x(1+2+3+...+20)=x(20+21)/2=x X 41/2=x X  20,5
X=ori