\(f\left(x\right)-g\left(x\right)=1+x+x^2+x^3+...+x^{100}-\left(x^2+x^4+...+x^{100}\right)\)
\(=1+x+x^3+x^5+...+x^{99}\)
Thay x=-1 vào f(x)-g(x) ta có:
\(f\left(x\right)-g\left(x\right)=1+\left(-1\right)+\left(-1\right)^3+\left(-1\right)^5+...+\left(-1\right)^{99}\)
\(=1-1-1-...-1=-1-1-...-1\left(49cs\right)\)
\(=-1.49=-49\)