Bài 1:
a) 6/2 x+ 1 = 2/7
6/2 x = 2/7 - 1
6/2 x = 2/7 - 7/7
6/2 x = -5/7
x = - 5/7 : 6/2
x = - 5/7 . 2/6
x = -5/21
Ủng hộ nha! :)
BÀI 1 a 6/2x+1=2/7
6/2x=2/7-1
6/2x=-5/7
6*7=5*2x
42=5*2x
42/5=2x
x=42/5:2
x=21/5
Bài 2 :
a) \(\frac{5^3.90.4^3}{25^2.3^2.2^{13}}=\frac{5^3.\left(2.5.3^2\right).2^6}{5^4.3^2.2^{13}}=\frac{2^7.3^2.5^4}{2^{13}.3^2.5^4}=\frac{1}{2^6}\)
b)\(\frac{15^2.16^4-15^3.16^3}{12^2.20^3-20^2.12^3}=\frac{15^2.16^3.\left(16-15\right)}{12^2.20^2\left(20-12\right)}\)
\(=\frac{15^2.16^3}{12^2.20^2.8}=\frac{\left(3^2.5^2\right).2^{12}}{\left(2^4.3^2\right).\left(2^4.5^2\right).2^3}\)
\(=\frac{2^{12}.3^2.5^2}{2^{11}.3^2.5^2}=2\)
c) \(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}=\frac{2.3.\left(1+2.2+7.7\right)}{3.5.\left(1+2.2+7.7\right)}\)\(=\frac{2}{5}\)
Bài 1 :
a) \(\frac{6}{2x+1}=\frac{2}{7}\Rightarrow2x+1=\frac{6.7}{2}\)
\(\Rightarrow2x+1=21\Rightarrow2x=20\Rightarrow x=10\)
b) \(\frac{x+46}{20}=x\frac{2}{5}\)
\(\Rightarrow\frac{x+46}{20}=\frac{x.5+2}{5}\)
\(\Rightarrow\frac{x+46}{20}=\frac{20x+8}{20}\)
\(\Rightarrow x+46=20x+8\Rightarrow x-20x=8-46\)
\(\Rightarrow-19x=-38\Rightarrow x=2\)
Bài 1 :
a) \(\frac{6}{2x+1}=\frac{2}{7}\)=) \(\frac{6}{2x+1}=\frac{6}{21}\)
=) \(2x+1=21\)=) \(2x=20\)=) \(x=20:2=10\)
b) \(x+\frac{46}{20}=x\frac{2}{5}\)=) \(x+\frac{23}{10}=x\frac{2}{5}\)
=) \(x+\frac{23}{10}=x+\frac{2}{5}\)=) \(x-x=\frac{2}{5}-\frac{23}{10}\)
=) \(0=\frac{-19}{10}\)( Vô lí ) =) Không tồn tại \(x\)=) \(x\in\)rỗng
Bài 2 :
a) \(\frac{5^3.90.4^3}{25^2.3^2.2^{13}}=\frac{5^3.\left(2.3^2.5\right).\left(2^2\right)^3}{\left(5^2\right)^2.3^2.2^{13}}=\frac{5^3.2.3^2.5.2^6}{5^4.3^2.2^{13}}\)
= \(\frac{5^4.3^2.2^7}{5^4.3^2.2^{13}}=\frac{2^7}{2^{13}}=\frac{1}{2^6}=\frac{1}{64}\)
c) \(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}=\frac{2.3.\left(1+4+49\right)}{3.5.\left(1+4+49\right)}=\frac{2.3}{3.5}=\frac{2}{5}\)
