Question

a)1 + 3 + 5 + 7....... + 2015

b) (2015 .2014 + 2014 . 2013)[1 + 1/2 : 1 \(\frac{1}{2}\) - 1\(\frac{1}{3}\)]

Answer 1

a) số số hạng

(2015-1) : 2+1=1008

tổng dãy số

1008 x (2015 +1) :2 = 1016064

 

Answer 2

a) 1+3+5+7+...+2015

Day tren co so so hang la:

(2015-1):2+1=1008(so hang)

Tong tren bang: (2015+1).1008:2=1016064

b) \(\left(2015.2014+2014.2013\right).\left(1+\frac{1}{2}:1\frac{1}{2}-1\frac{1}{3}\right)\) 

= \(\left(2015.2014+2014.2013\right).\left(1+\frac{1}{2}:\frac{3}{2}-\frac{4}{3}\right)\) 

= \(\left(2015.2014+2014.2013\right).\left(1+\frac{1}{2}.\frac{2}{3}-\frac{4}{3}\right)\) 

= \(\left(2015.2014+2014.2013\right).\left(1+\frac{1}{3}-\frac{4}{3}\right)\) 

= \(\left(2015.2014+2014.2013\right).\left(\frac{4}{3}-\frac{4}{3}\right)\) 

=\(\left(2015.2014+2014.2013\right).0\)

= \(0\)