M(x) = x3 - 30x2 - 31x + 1
= (x3 - 31x2) + (x2 - 31x) + 1
= x2(x - 31) + x(x - 31) + 1
= 1
x3-30x2-31x+1
=(x3-31x2)+(x2-31x)+1
=x2(x-31)+x(x-31)+1
=(x2+x)(x-31)+1
Thay x=31, ta đc M(X)=1
M(x) = x3 - 30x2 - 31x + 1
= (x3 - 31x2) + (x2 - 31x) + 1
= x2(x - 31) + x(x - 31) + 1
= 1