Question

1) Quy đồng mẫu:

a) \(\dfrac{4}{7};\dfrac{13}{9};\dfrac{8}{21}\)

b)\(\dfrac{1}{-36};\dfrac{-8}{45};\dfrac{13}{90}\)

c)\(3;-1;\dfrac{17}{23}\)

các bạn giúp mình với mai mk nộp co cô rùi

Answer 1

a) \(\dfrac{4}{7}=\dfrac{4\cdot9}{7\cdot9}=\dfrac{36}{63}\)

\(\dfrac{13}{9}=\dfrac{13\cdot7}{9\cdot7}=\dfrac{91}{63}\)

\(\dfrac{8}{21}=\dfrac{8\cdot3}{21\cdot3}=\dfrac{24}{63}\)

b) \(\dfrac{1}{-36}=\dfrac{1\cdot5}{-36\cdot5}=\dfrac{-5}{180}\)

\(\dfrac{-8}{45}=\dfrac{-8\cdot4}{45\cdot4}=\dfrac{-32}{180}\)

\(\dfrac{13}{90}=\dfrac{13\cdot2}{90\cdot2}=\dfrac{26}{180}\)

c) \(3=\dfrac{3}{1}=\dfrac{3\cdot23}{1\cdot23}=\dfrac{69}{23}\)

\(-1=\dfrac{-1}{1}=\dfrac{-1\cdot23}{1\cdot23}=\dfrac{-23}{23}\)

\(\dfrac{17}{23}\) giữ nguyên