(X-1).(1/2+1/6+1/12+1/20+1/30)=2/3

2 bình luận về “(X-1).(1/2+1/6+1/12+1/20+1/30)=2/3”

1. (x-1)(1/2+1/6+1/12+1/20+1/30)=2/3

   <=>(x-1)(1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6) )=2/3

   <=>(x-1)(1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6)=2/3

   <=>(x-1)(1/1-1/6)=2/3

   <=>(x-1)(6/6-1/6)=2/3

   <=>(x-1)*5/6=2/3

   <=>x-1=2/3:5/6

   <=>x-1=2/3xx6/5

   <=>x-1=4/5

   <=>x=4/5+1

   <=>x=4/5+5/5

   <=>x=9/5

   Trả lời
2. $\text{Giải đáp$+$Lời giải và giải thích chi tiết:}$

   $($$x$$-$$1$$)$$.$$($$\dfrac{1}{2}$$+$$\dfrac{1}{6}$$+$$\dfrac{1}{12}$$+$$\dfrac{1}{20}$$+$$\dfrac{1}{30}$$)$$=$$\dfrac{2}{3}$

   $($$x$$-$$1$$)$$.$$($$\dfrac{30}{60}$$+$$\dfrac{10}{60}$$+$$\dfrac{5}{60}$$+$$\dfrac{3}{60}$$+$$\dfrac{2}{60}$$)$$=$$\dfrac{2}{3}$

   $($$x$$-$$1$$)$$.$$\dfrac{5}{6}$$=$$\dfrac{2}{3}$

   $x$$-$$1$$=$$\dfrac{2}{3}$$:$$\dfrac{5}{6}$

   $x$$-$$1$$=$$\dfrac{4}{5}$

   $x$$=$$\dfrac{4}{5}$$+$$1$

   $x$$=$$\dfrac{9}{5}$

   Trả lời