Có x = 100
<=> x + 1 = 101
Ta có :
\(f\left(x\right)=x^8-101.x^7+101.x^6-101.x^5+......+101x^2-101x+25\)
\(f\left(x\right)=x^8-\left(x+1\right).x^7+\left(x+1\right).x^6-\left(x+1\right).x^5+....+\left(x+1\right).x^2-\left(x+1\right).x+25\)
\(f\left(x\right)=x^8-x^8-x^7+x^7+x^6-x^6-x^5+.....+x^3-x^2+x^2+x+25\)
\(f\left(x\right)=x+25\)
\(f\left(100\right)=100+25=125\)