Quy đồng mẫu thức các phân thức sau:
a) m/m3--8 ;3m/m2-4m+4;1/m2+2m+4
b)y2-1/6y2--11y-10;y+1/3y2-4y-4
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\(a,\dfrac{7x-1}{2x^2+6x}=\dfrac{\left(7x-1\right)\left(x-3\right)}{2x\left(x+3\right)\left(x-3\right)}=\dfrac{7x^2-22x+3}{2x\left(x-3\right)\left(x+3\right)}\\ \dfrac{5-3x}{x^2-9}=\dfrac{2x\left(5-3x\right)}{2x\left(x-3\right)\left(x+3\right)}=\dfrac{10x-6x^2}{2x\left(x-3\right)\left(x+3\right)}\)
Ta có:
x 3 + 6 x 2 + 12 x + 8 = x 3 + 3 x 2 . 2 + 3 . x . 2 2 + 2 3 = x + 2 3
x 2 + 4 x + 4 = x + 2 2 ; 2 x + 4 = 2 x + 2
Mẫu thức chung: 2 x + 2 3

Bài 2:
a: 1/3=20/60
1/5=12/60
1/12=5/60
b: 1/3=16/48
1/12=4/48
1/48=1/48
Bài 2:
a: 1/3=20/60
1/5=12/60
1/12=5/60
b: 1/3=16/48
1/12=4/48
1/48=1/48
Bài 2:
a: 1/3=20/60
1/5=12/60
1/12=5/60
b: 1/3=16/48
1/12=4/48
1/48=1/48
a) \(\dfrac{1}{3}=\dfrac{1.8}{3.8}=\dfrac{8}{24}\)
\(\dfrac{3}{4}=\dfrac{3.6}{4.6}=\dfrac{18}{24}\)
\(\dfrac{5}{8}=\dfrac{5.3}{8.3}=\dfrac{15}{24}\)
b) \(\dfrac{2}{3}=\dfrac{2.4}{3.4}=\dfrac{8}{12}\)
\(\dfrac{3}{4}=\dfrac{3.3}{4.3}=\dfrac{9}{12}\)
\(\dfrac{7}{12}=\dfrac{7}{12}\)
c) \(\dfrac{1}{5}=\dfrac{1.6}{5.6}=\dfrac{6}{30}\)
\(\dfrac{1}{6}=\dfrac{1.5}{6.5}=\dfrac{5}{30}\)
\(\dfrac{1}{30}=\dfrac{1}{30}\)
\(\frac{3}{6-2x}=\frac{-3}{2\left(x-3\right)}=\frac{-3\cdot3}{2\left(x-3\right)\cdot3}=\frac{-9}{6\left(x-3\right)}\)
\(\frac{2}{x-3}=\frac{2\cdot6}{6\left(x-3\right)}=\frac{12}{6\left(x-3\right)}\)
\(\frac{-5}{3x-9}=\frac{-5}{3\left(x-3\right)}=\frac{-5\cdot2}{3\left(x-3\right)\cdot2}=\frac{-10}{6\left(x-3\right)}\)
\(\frac{7}{4-2x}=\frac{-7}{2\left(x-2\right)}=\frac{-7\cdot\left(x-2\right)}{2\left(x-2\right)\left(x-2\right)}=\frac{-7x+14}{2\left(x-2\right)^2}\)
\(\frac{2}{x^2-4x+4}=\frac{2}{\left(x-2\right)^2}=\frac{2\cdot2}{\left(x-2\right)^2\cdot2}=\frac{4}{2\left(x-2\right)^2}\)