a)C1:\(-\left(\dfrac{2}{5}-\dfrac{3}{4}\right)-\left(\dfrac{3}{4}+\dfrac{3}{5}\right)\)
=\(-\left(-\dfrac{7}{20}\right)-\left(\dfrac{3}{4}+\dfrac{3}{5}\right)\)
=\(\dfrac{7}{20}-\left(\dfrac{3}{4}+\dfrac{3}{5}\right)\)
=\(\dfrac{7}{20}-\dfrac{27}{20}\)
=\(-1\)
C2:\(-\left(\dfrac{2}{5}-\dfrac{3}{4}\right)-\left(\dfrac{3}{4}+\dfrac{3}{5}\right)\)
=\(-\dfrac{2}{5}+\dfrac{3}{4}+\left[\left(-\dfrac{3}{4}\right)+\left(-\dfrac{3}{5}\right)\right]\)
=\(\left[\left(-\dfrac{2}{5}\right)+\left(-\dfrac{3}{5}\right)\right]+\left[\dfrac{3}{4}+\left(-\dfrac{3}{4}\right)\right]\)
=\(-1+0\)
=\(-1\)
a) C1:
\(-\left(\dfrac{2}{5}-\dfrac{3}{4}\right)-\left(\dfrac{3}{4}+\dfrac{3}{5}\right)\)= \(-\left(\dfrac{8}{20}-\dfrac{15}{20}\right)-\left(\dfrac{15}{20}+\dfrac{12}{20}\right)\)= \(\dfrac{7}{20}-\dfrac{27}{20}=\dfrac{-20}{20}=-1\)
C2:
\(-\left(\dfrac{2}{5}-\dfrac{3}{4}\right)-\left(\dfrac{3}{4}+\dfrac{3}{5}\right)\)=\(-\dfrac{2}{5}+\dfrac{3}{4}-\dfrac{3}{4}-\dfrac{3}{5}\)= \(-\dfrac{2}{5}-\dfrac{3}{5}=-\dfrac{5}{5}=-1\)
b)\(\dfrac{2^{15}.9^4}{6^6.8^3}\)
=\(\dfrac{2^9.2^6\left(3^2\right)^4}{3^6.2^6.\left(2^3\right)^3}\)
=\(\dfrac{2^9.3^8}{3^6.2^9}\)
=\(3^2\)
b) \(\dfrac{2^{15}.9^4}{6^6.8^3}=\dfrac{2^{15}.\left(3^2\right)^4}{\left(3.2\right)^6.\left(2^3\right)^3}=\dfrac{2^{15}.3^8}{3^6.2^6.2^9}=\dfrac{2^{15}.3^8}{3^6.2^{15}}=3^2=9\)
P/s nhớ tick cho mình hết bài nha. Thanks bạn
