`26/54=(26:2)/(54:2)=13/27`

\(\dfrac{26}{54}=\dfrac{26:2}{54:2}=\dfrac{13}{27}\)

Rút gọn phân số12 Phần 26

9/56

9/56

\(\dfrac{9}{56}\)

36/48= 3/4

-27/45= -3/5

-26/-39= 2/3

= 3/4

= -3/5

= 2/3

\(\dfrac{36}{48}=\dfrac{36:12}{48:12}=\dfrac{3}{4}\\ \dfrac{-27}{45}=\dfrac{-27:9}{45:9}=\dfrac{-3}{5}\\ \dfrac{-26}{-39}=\dfrac{26}{39}=\dfrac{26:13}{39:13}=\dfrac{2}{3}\)

B

`=>B`

b

a) Ta có: \(M=\dfrac{2}{\sqrt{7}-\sqrt{6}}-\sqrt{28}+\sqrt{54}\)

\(=\dfrac{2\left(\sqrt{7}+\sqrt{6}\right)}{\left(\sqrt{7}-\sqrt{6}\right)\left(\sqrt{7}+\sqrt{6}\right)}-2\sqrt{7}+3\sqrt{6}\)

\(=2\sqrt{7}+2\sqrt{6}-2\sqrt{7}+3\sqrt{6}\)

\(=5\sqrt{6}\)

b) Ta có: \(N=\left(2-\sqrt{3}\right)\left(\sqrt{26+15\sqrt{3}}\right)-\left(2+\sqrt{3}\right)\sqrt{26-15\sqrt{3}}\)

\(=\dfrac{\left(2-\sqrt{3}\right)\sqrt{52+30\sqrt{3}}-\left(2+\sqrt{3}\right)\sqrt{52-30\sqrt{3}}}{\sqrt{2}}\)

\(=\dfrac{\left(2-\sqrt{3}\right)\sqrt{27+2\cdot3\sqrt{3}\cdot5+25}-\left(2+\sqrt{3}\right)\sqrt{27-2\cdot3\sqrt{3}\cdot5+25}}{\sqrt{2}}\)

\(=\dfrac{\left(2-\sqrt{3}\right)\sqrt{\left(3\sqrt{3}+5\right)^2}-\left(2+\sqrt{3}\right)\sqrt{\left(3\sqrt{3}-5\right)^2}}{\sqrt{2}}\)

\(=\dfrac{\left(2-\sqrt{3}\right)\left(3\sqrt{3}+5\right)-\left(2+\sqrt{3}\right)\left(3\sqrt{3}-5\right)}{\sqrt{2}}\)

\(=\dfrac{6\sqrt{3}+10-9-5\sqrt{3}-\left(6\sqrt{3}-10+9-5\sqrt{3}\right)}{\sqrt{2}}\)

\(=\dfrac{\sqrt{3}+1-\sqrt{3}+1}{\sqrt{2}}\)

\(=\dfrac{2}{\sqrt{2}}=\sqrt{2}\)

Rút gọn P/S : \(\frac{81}{54}\)

\(\frac{81}{54}=\frac{81:9}{54:9}=\frac{9}{6}=\frac{9:3}{6:3}=\frac{3}{2}\)

@Trunglaai?

là = 3/2

\(\dfrac{75}{100}=\dfrac{3}{4};\dfrac{63}{126}=\dfrac{1}{2}\\ \dfrac{36}{27}=1\dfrac{1}{3};\dfrac{81}{54}=1\dfrac{1}{2};\dfrac{105}{405}=\dfrac{7}{27}\)

\(\dfrac{3}{4}\)

\(\dfrac{1}{2}\)

\(\dfrac{4}{3}\)

\(\dfrac{3}{2}\)

\(\dfrac{4}{15}\)

75/100= 75:25/100:25= 3/4

63/126= 63:63/126:63= 1/2

36/27= 36:6/27:9= 4/3

81/54= 81:27/54:27= 3/2

108/405= 108:27/404:27=4/15