Question

Hãy vận dụng tính chất cơ bản của phép nhân để tính giá trị các biểu thức sau:

B=\(\dfrac{2}{17}.\dfrac{-15}{23}.\dfrac{17}{2}\);C=\(\dfrac{-1}{9}.\dfrac{3}{21}-\dfrac{3}{21}.\dfrac{8}{9}\)

Answer 1

B=\(\dfrac{2.\left(-15\right).17}{17.23.2}=\dfrac{-15}{23}\)

C=\(\dfrac{3}{21}.\left(\dfrac{-1}{9}+\dfrac{-8}{9}\right)=\dfrac{3}{21}.\left(-1\right)=\dfrac{-1}{7}\)

Answer 2

dễ thôi

B=\(\dfrac{2}{17}\).\(\dfrac{-15}{23}\).\(\dfrac{17}{2}\)

B=\(\dfrac{2}{17}\).\(\dfrac{17}{2}\).\(\dfrac{-15}{23}\)

B=1.\(\dfrac{-15}{23}\)

B=\(\dfrac{-15}{23}\)

C=\(\dfrac{-1}{9}\).\(\dfrac{3}{21}\)-\(\dfrac{3}{21}\).\(\dfrac{8}{9}\)

C=\(\dfrac{3}{21}\).(\( \dfrac{-1}{9}\)-\(\dfrac{8}{9}\))

C=\(\dfrac{1}{7}\).(-1)

C=\(\dfrac{-1}{7}\)

đó hết rùi . toàn bộ phần bài