Quy đồng mẫu thức các phân thức sau :
a) \(\dfrac{5}{x^5y^3},\dfrac{7}{12x^3y^4}\)
b) \(\dfrac{4}{15x^3y^5},\dfrac{11}{12x^4y^2}\)
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\(\dfrac{5}{x^5y^3};\dfrac{7}{12x^3y^4}\)
\(MTC=12x^5y^4\)
Ta có:
\(\dfrac{5}{x^5y^3}=\dfrac{60y}{12x^5y^4}\)
\(\dfrac{7}{12x^3y^4}=\dfrac{7x^2}{12x^5y^4}\)
Bài 2:
a: \(\dfrac{1}{2x^3y}=\dfrac{6yz^3}{12x^3y^2z^3}\)
\(\dfrac{2}{3xy^2z^3}=\dfrac{2\cdot4x^2}{12x^3y^2z^3}=\dfrac{8x^2}{12x^3y^2z^3}\)
2x−3y/5=5y−2z/3=3z−5x/2=10x-15y/25=15y-6z/9=6z-10x/4=...+..+..../25+9+4=0/31=0
=> 2x=3y; 5y=2z ; 3z=5x => x/3=y/2; y/2=z/5
=> x/3=y/2 =z/5 = 12x/36=5y/10=3z/15= (12x+5y-3z)/31
x/3 = 3y/6=2z/10 = (x-3y+2z)/7
=> (12x+5y-3z)/ (x-3y+2z)=31/7
a) MTC: \(12x^3y^3\)
\(\dfrac{3}{4x^3y^2}=\dfrac{3\cdot3y}{4x^3y^2\cdot3y}=\dfrac{9y}{12x^3y^3}\)
\(\dfrac{2}{3xy^3}=\dfrac{2\cdot4x^2}{3xy^3\cdot4x^2}=\dfrac{8x^2}{12x^3y^3}\)
b) MTC: \(x\left(x-3\right)^2\)
\(\dfrac{5}{x^2-6x+9}=\dfrac{5}{\left(x-3\right)^2}=\dfrac{5x}{x\left(x-3\right)^2}\)
\(\dfrac{3}{x^2-3x}=\dfrac{3}{x\left(x-3\right)}=\dfrac{3\left(x-3\right)}{x\left(x-3\right)^2}=\dfrac{3x-9}{x\left(x-3\right)^2}\)
a) Tìm MTC:
2x + 6 = 2(x + 3)
x2 – 9 = (x – 3)(x + 3)
MTC = 2(x – 3)(x + 3) = 2(x2 – 9)
Nhân tử phụ:
2(x – 3)(x + 3) : 2(x + 3) = x – 3
2(x – 3)(x + 3) : (x2 – 9) = 2
Qui đồng:
b) Tìm MTC:
x2 – 8x + 16 = (x – 4)2
3x2 – 12x = 3x(x – 4)
MTC = 3x(x – 4)2
Nhân tử phụ:
3x(x – 4)2 : (x – 4)2 = 3x
3x(x – 4)2 : 3x(x – 4) = x – 4
Qui đồng:
click mh nha
a)MTC:\(12x^5y^4\)
\(\dfrac{5}{x^5y^3}=\dfrac{5\cdot12y}{x^5y^3\cdot12y}=\dfrac{60y}{12x^5y^4}\)
\(\dfrac{7}{12x^3y^4}=\dfrac{7\cdot x^2}{12x^3y^4\cdot x^2}=\dfrac{7x^2}{12x^5y^4}\)
b)MTC:\(60x^4y^5\)
\(\dfrac{4}{15x^3y^5}=\dfrac{4\cdot4x}{15x^3y^5\cdot4x}=\dfrac{16x}{60x^4y^5}\)
\(\dfrac{11}{12x^4y^2}=\dfrac{11\cdot5y^3}{12x^4y^2\cdot5y^3}=\dfrac{55y^3}{60x^4y^5}\)