`a,A=100^2−99^2+98^2−97^2+...+2^2−1^2`
`=(100−99)(100+99)+(98−97)(98+97)+...+(2−1)(2+1)`
`=(1+100).100:2`
`=5050`
`b,B=3(2^2+1)(2^4+1)...(2^64+1)+1^2`
`=(2^2−1)(2^2+1)(2^4+1)(2^8+1)....(2^64+1)+1`
`=(2^16−1)(2^16+1)(2^32+1)....(2^64+1)+1`
`=2^128−1+1=2^128`
`c,C=(a+b+c)^2+(a+b−c)^2−2(a+b)^2`
`=a^2+b^2+c^2+2ab+2ac+2bc+a^2+b^2+c^2+2ab−2ac−2bc−2(a^2+2ab+b^2)`
`=2c^2+0+0+0`
`=2c^2`