Question

Giải ra cho mình nha.

Answer 1

Với mọi \(n>0;n\in N\) ta có:

\(1^3+2^3+3^3+...+n^3=\left(1+2+3+...+n\right)^2=\left(\dfrac{n\left(n+1\right)}{2}\right)^2\)

Khi đó \(VT=\left(1+2+3+4+...+23+24\right)^2\)

\(=\left(\dfrac{24\cdot\left(24+1\right)}{2}\right)^2=\left(\dfrac{24\cdot25}{2}\right)^2=300^2=90000\)

\(\Rightarrow VT=VP=x^2\Rightarrow90000=x^2\)

Mà \(x>0\)\(\Rightarrow x=\sqrt{90000}=300\)

Answer 2

x=\(\dfrac{24.25}{2}\)=12.25=3.100=300