Question

A=(1-1/2^2)(1-1/3^2).....(1-1/10^2) mọi nhười giúp e với ạ:((

 

 

Answer 1

(1 - 1/2^2)(1 - 1/3^2).......(1 - 1/10^2)

= ( 2^2 -1/2^2)(3^2-1/3^2).......(10^2-1/10^2)

= (4-1/2.2)(9-1/3.3)......(100-1/10.10)

=3/2.2 . 8/3.3..........99/10.10

=1.3/2.2 . 2.4/3.3........9.11/10.10

=(1/2 . 2/3 . ........ 9/10)(3/2 . 4/3......... 11/10)

= 1/10 . 11/2

= 11/20

Answer 2

A=(1-1/2²)(1-1/3²).......(1-1/10²)

   =(1-1/4)(1-1/9)......(1-1/100)

   =3/4.8/9......99/100

   =1.3.2.4...9.11/(2.3....10)²

    =1.2.3....11/(3...10).10

    =2.11/10

    =22/10

    =11/5