\(\left|x\right|\le5\)
\(\Rightarrow\left|x\right|\in\left\{0;1;2;3;4;5\right\}\)
\(\Rightarrow x\in\left\{0;\pm1;\pm2;\pm3;\pm4;\pm5\right\}\)
Tổng các số nguyên x thỏa mãn là :
\(0+\left(-1\right)+1+\left(-2\right)+2+\left(-3\right)+3+\left(-4\right)+4+\left(-5\right)+5\)
\(=0+\left[\left(-1\right)+1\right]+\left[\left(-2\right)+2\right]+\left[\left(-3\right)+3\right]+\left[\left(-4\right)+4\right]+\left[\left(-5\right)+5\right]\)
\(=0+0+0+0+0+0=0\)
/x/ ≤ 5
=> /x/ ∈{0;1;2;3;4;5}
=> x ∈ {-5;-4;-3;-2;-1;0;1;2;3;4;5}
Ta có :-5 + (-4) + (-3) + (-2) + (-1) + 0 + 1 + 2 + 3 + 4 + 5
= (-5+5)+(-4+4)+(-3+3)+(-2+2)+(-1+1)+0
= 0+0+0+0+0+0
=0
|x|≤5
⇒|x|∈{0;1;2;3;4;5}
⇒x∈{0;±1;±2;±3;±4;±5}
Tổng các số nguyên x thỏa mãn là :
=0+[(−1)+1]+[(−2)+2]+[(−3)+3]+[(−4)+4]+[(−5)+5]=0+[(−1)+1]+[(−2)+2]+[(−3)+3]+[(−4)+4]+[(−5)+5]
=0+0+0+0+0+0
=0
