Question

\(\text{Tính giá trị biểu thức bằng cách hợp lí }\)

\(\text{b) 263^2+74.263+37^2 }\)

\(\text{c) 136^2-92.136+46^2}\)

\(\text{d) (50^2+48^2+46^2+.....+2^2)-(49^2+47^2+45^2+....+1^2)}\)

Answer 1

b) \(263^2+74.263+37^2\)

\(=\left(263+37\right)^2\)

\(=300^2\)

\(=90000\)

Answer 2

c) \(136^2-92.136+46^2\)

\(=\left(136-46\right)^2\)

\(=90^2\)

\(=8100\)

Answer 3

cảm ơn lê tài bảo châu nhé

Answer 4

d) \(\left(50^2+48^2+...+2^2\right)-\left(49^2+47^2+...+1^2\right)\)

\(=\left(50^2-49^2\right)+\left(48^2-47^2\right)+...+\left(2^2-1^2\right)\)

\(=\left(50-49\right)\left(50+49\right)+\left(48-47\right)\left(48+47\right)+...+\left(2-1\right)\left(2+1\right)\)

\(=99+95+...+3\)

\(=\frac{\left[\left(99-3\right):4+1\right]\left(99+3\right)}{2}\)

\(=1224\)