Answer:
\(A=127^2+146.127+73^2\)
\(=127^2+2.127.73+73^2\)
\(=\left(127+73\right)^2\)
\(=200^2\)
\(=40000\)
\(B=9^8.2^8-\left(18^4-1\right)\left(18^4+1\right)\)
\(=\left(9.2\right)^8-[\left(18^4\right)^2-1]\)
\(=18^8-18^8+1\)
\(=1\)
\(C=\left(20^2+18^2+16^2+...+4^2+2^2\right)-\left(19^2+17^2+15^2+...+3^2+1^2\right)\)
\(=20^2+18^2+16^2+...+4^2+2^2-19^2-17^2-15^2-...-3^2-1^2\)
\(=\left(20^2-19^2\right)+\left(18^2-17^2\right)+...+\left(2^2-1^2\right)\)
\(=\left(20-19\right)\left(20+19\right)+\left(18-17\right)\left(18+17\right)+...+\left(2-1\right)+\left(2+1\right)\)
\(=1.39+1.35+...+1.3\)
\(=39+35+...+3\)
Số số hạng \(\frac{39-3}{4}+1=10\) số hạng
Tổng \(\frac{\left(39+3\right).10}{2}=210\)
