Nguyễn Vũ Thùy Trâm
Giới thiệu về bản thân
Các số nguyên \(x\) thoả mãn \(- 4 \leq x \leq 5\) gồm \(- 4 ; - 3 ; - 2 ; - 1 ; 0 ; \&\text{nbsp}; 1 ; 2 ; \&\text{nbsp}; 3 ; 4 ; 5\).
Tổng cần tính là \(\left(\right. - 4 \left.\right) + \left(\right. - 3 \left.\right) + \left(\right. - 2 \left.\right) + \left(\right. - 1 \left.\right) + 0 + 1 + 2 + 3 + 4 + 5\). Áp dụng tính chất giao hoán, kết hợp của phép cộng các số nguyên ta viết lại tổng trên thành:
\(\left[\right. \left(\right. - 4 \left.\right) + 4 \left]\right. + \left[\right. \left(\right. - 3 \left.\right) + 3 \left]\right. + \left[\right. \left(\right. - 2 \left.\right) + 2 \left]\right. + \left[\right. \left(\right. - 1 \left.\right) + 1 \left]\right. + 0 + 5\)
\(= 0 + 5\)
$ =5$.
Ta có \(\left(\right. - 4 \left.\right)^{2} . \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 11 + 8 \left.\right)^{3} \left]\right.\)
\(= 16. \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 3 \left.\right)^{3} \left]\right.\)
\(= - 48 - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 27 \left.\right) \left]\right.\)
\(= - 48 - \left(\right. - 120 \left.\right)\)
\(= 72\).
Ta có \(\left(\right. - 4 \left.\right)^{2} . \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 11 + 8 \left.\right)^{3} \left]\right.\)
\(= 16. \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 3 \left.\right)^{3} \left]\right.\)
\(= - 48 - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 27 \left.\right) \left]\right.\)
\(= - 48 - \left(\right. - 120 \left.\right)\)
\(= 72\).
Ta có \(\left(\right. - 4 \left.\right)^{2} . \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 11 + 8 \left.\right)^{3} \left]\right.\)
\(= 16. \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 3 \left.\right)^{3} \left]\right.\)
\(= - 48 - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 27 \left.\right) \left]\right.\)
\(= - 48 - \left(\right. - 120 \left.\right)\)
\(= 72\).
Ta có \(\left(\right. - 4 \left.\right)^{2} . \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 11 + 8 \left.\right)^{3} \left]\right.\)
\(= 16. \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 3 \left.\right)^{3} \left]\right.\)
\(= - 48 - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 27 \left.\right) \left]\right.\)
\(= - 48 - \left(\right. - 120 \left.\right)\)
\(= 72\).
Ta có \(\left(\right. - 4 \left.\right)^{2} . \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 11 + 8 \left.\right)^{3} \left]\right.\)
\(= 16. \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 3 \left.\right)^{3} \left]\right.\)
\(= - 48 - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 27 \left.\right) \left]\right.\)
\(= - 48 - \left(\right. - 120 \left.\right)\)
\(= 72\).
Ta có \(\left(\right. - 4 \left.\right)^{2} . \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 11 + 8 \left.\right)^{3} \left]\right.\)
\(= 16. \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 3 \left.\right)^{3} \left]\right.\)
\(= - 48 - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 27 \left.\right) \left]\right.\)
\(= - 48 - \left(\right. - 120 \left.\right)\)
\(= 72\).
Ta có \(\left(\right. - 4 \left.\right)^{2} . \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 11 + 8 \left.\right)^{3} \left]\right.\)
\(= 16. \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 3 \left.\right)^{3} \left]\right.\)
\(= - 48 - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 27 \left.\right) \left]\right.\)
\(= - 48 - \left(\right. - 120 \left.\right)\)
\(= 72\).
Ta có \(\left(\right. - 4 \left.\right)^{2} . \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 11 + 8 \left.\right)^{3} \left]\right.\)
\(= 16. \left(\right. - 3 \left.\right) - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 3 \left.\right)^{3} \left]\right.\)
\(= - 48 - \left[\right. \left(\right. - 93 \left.\right) + \left(\right. - 27 \left.\right) \left]\right.\)
\(= - 48 - \left(\right. - 120 \left.\right)\)
\(= 72\).
Vì 2012 hơn 2011 một đơn vị còn 2018 lại kém 2019 một đơn vị nên 2012 + 2018 = 2011 + 2019.
Tương tự, 2014 + 2016 = 2013 + 2017 = 2012 + 2018 = 20 11 + 2019 = 4030.
Sử dụng tính chất giao hoán và tính chất kết hợp của phép cộng viết lại tổng cần tính thành:
(2011 + 2019) + (2012 + 2018) + (2013 + 2017) + (2014 + 2016) + 2015
= 4030 + 4030 + 4030 + 4030 + 2015 = 4 . 4030 + 2015 = 18 135