Question

[Vinh Manh]

cho biểu thức:A=[6\(\times\left(-\frac{1}{3}\right)^2-3\times\left(-\frac{1}{3}\right)+1\)]\(\div\left(-\frac{1}{3}-1\right)\)

B=\(\left(729-1^3\right)\times\left(729-3^3\right)\times...\times\left(729-125^3\right)\)

hãy so sánh A và B

nhanh lên mai mình phải nộp rồi

Answer 1

[Nguyễn Huy Tú]

Ta có: \(A=\left[6.\left(-\frac{1}{3}\right)^2-3.\left(-\frac{1}{3}\right)+1\right]:\left(\frac{-1}{3}-1\right)\)

\(=\left(6.\frac{1}{9}-\left(-1\right)+1\right):\left(\frac{-4}{3}\right)\)

\(=\left(\frac{2}{3}+2\right).\left(\frac{-3}{4}\right)\)

\(=\frac{8}{3}.\left(-\frac{3}{4}\right)\)

\(=-2\)

\(B=\left(729-1^3\right)\left(729-3^3\right)...\left(729-125^3\right)\)

\(\Rightarrow B=\left(729-1^3\right)\left(729-3^3\right)...\left(729-9^3\right)...\left(729-125^3\right)\)

\(\Rightarrow B=\left(729-1^3\right)\left(729-3^3\right)...0...\left(729-125^3\right)\)

\(\Rightarrow B=0\)

Vì -2 < 0 nên A < B

Vậy A < B