Question

Answer 1

a)

\(A=x^3+3x^2+3x+1\)

\(A=\left(x+1\right)^3\)

Thay x = 19 vào A ta có:

\(A=\left(19+1\right)^3=20^3=8000\)

b)

\(B=x^3-15x^2+75x-125\)

\(B=x^3-3\cdot x^2\cdot5+3\cdot5^2\cdot x-5^3\)

\(B=\left(x-5\right)^3\)

Thay x = 15 vào B ta có:

\(B=\left(15-5\right)^3=10^3=1000\)

Answer 2

A = \(x^3+3x^2+3x+1\)

A = \(\left(x+1\right)^3\)

A = \(\left(19+1\right)^3=20^3\)

A = \(8000\)

B = \(x^3-15x^2+75x-125\)

B = \(\left(x-5\right)^3\)

B = \(\left(15-5\right)^3\) = \(10^3=1000\)