Question

a/Tính nhanh:

1 x 2 x 3 + 2 x 4 x 6 + 3 x 6 x 9 + 4 x 8 x 12

b/So sánh A và B biết:

A=2010 +2011 / 2011 +2012                         B=2010/2011 + 2011/2012

ai đúng thì mình sẽ tick nha

a

Answer 1

a. 1⋅2⋅3+2⋅4⋅6+3⋅6⋅9+4⋅8⋅12

= 6+2⋅4⋅6+3⋅6⋅9+4⋅8⋅12

= 6+48+3⋅6⋅9+4⋅8⋅12

= 6+48+162+4⋅8⋅12

= 6+48+162+384

= 600

Answer 2

b . Ta có \(A=\frac{2010+2011}{2011+2012}=\frac{2010}{2011+2012}+\frac{2011}{2011+2012}.\)

Ta có : \(\frac{2010}{2011+2012}< \frac{2010}{2011}\) và \(\frac{2011}{2011+2012}< \frac{2011}{2012}\)

=> \(\frac{2010+2011}{2011+2012}< \frac{2010}{2011}+\frac{2011}{2012}\)

=> A < B