Cho

- Hướng dẫn giải

$$\begin{gathered} M – N = {77}^2 + {75}^2 + {73}^2 + \dots + 3^2 + 1^2 – ({76}^2 + {74}^2 + \dots + 2^2) \\ = ({77}^2 – {76}^2) + ({75}^2 – {74}^2) + ({73}^2 – {71}^2) + \dots + (3^2 – 2^2) + 1^2 \\ = (77 + 76)(77 – 76) + (75 + 74)(75 – 74) + \dots + (3 + 2)(3 – 2) + 1 \\ = (77 + 76).1 + (75 + 74).1 + \dots + (3 + 2).1 + 1 \\ = 77 + 76 + 75 + 74 + 73 + \dots + 3 + 2 + 1 \\ =\frac{77+1}{2}.77 \\ =3003 \end{gathered}$$

$\Rightarrow \frac{M-N-3}{3000}=\frac{3003-3}{3000}=\frac{3000}{3000}=1$

Đáp án cần chọn là: C