When Xiaojun calculates the polynomial (x ^ 2 + MX + n) (x ^ 2-4x), he finds that the expansion does not contain x ^ 3 and x ^ 2. He tries to find the value of M and n

When Xiaojun calculates the polynomial (x ^ 2 + MX + n) (x ^ 2-4x), he finds that the expansion does not contain x ^ 3 and x ^ 2. He tries to find the value of M and n

(x^2+mx+n)(x^2-4x)
=x^4-4x^3+mx^3-4mx^2+nx^2-4nx
=x^4+(m-4)x^3+(n-4m)x^2-4nx
Because it doesn't contain x ^ 3 and x ^ 2
therefore
m-4=0
n-4m=0
m=4
n=16

If the polynomials x3-2x2-4x-1 and (x + 1) (x2 + MX + n) are equal regardless of the value of X, find the value of M and n

∵ polynomials x3-2x2-4x-1 and (x + 1) (x2 + MX + n) are equal, ∵ x3-2x2-4x-1 = (x + 1) (x2 + MX + n) = X3 + (M + 1) x2 + (n + m) x + N, ∵ m + 1 = - 2, n = - 1, M + n = - 4, ∵ M = - 3, n = - 1

No matter what value x takes, the values of polynomial X & # 179; - 2x & # 178; - 4x-1 and (x + 1) (X & # 178; + MX + n) are equal, and the values of M and N are obtained

M = - 3, n = - 1