Question

Ma puteti ajuta cu aceste exercitii?

Answer 1

[tex]1.f:R\rightarrow R,f(x)=2x+1\\ f(1)+f(2)+f(3)+...+f(10)=\\ 2+1+2\cdot2+1+2\cdot3+1+...+2\cdot10+1=\\ 2(1+2+3+...+10)+10=\\ \not 2\cdot\frac{10\cdot11}{\not 2}+10=\\ 110+10=\boxed{120}\\ \\ 2.f:R\rightarrow R,f(x)=1+x\\ f(-1)+f(-2)+f(-3)+...+f(-10)=\\ 1-1+1-2+1-3+...+1-10=\\ 10-(1+2+3+...+10)=\\ 10-\frac{10\cdot11}{2}=\\ 10-55=\boxed{-45}[/tex]