2+4+6+8...........+208+210 = ?

Question

螞蟻雄兵 · Accepted Answer

2+4+6+8...........+208+210 = ?
Sol
A=2+4+6+…+206+208+210
A=210+208+206+…+6+4+2
2A=(2+210)+(4+208)+(6+2-6)+…+(206+6)+(208+4)+(210+2)
=212*(210/2)
=212*105
=22260
A=11130
or
項數=210/2=105
2+4+6+8...........+208+210
=(2+210)*105/2
=106*105
=11130

? · Answer

= 2*(1+105)*105/2
= 105*106

家駒 · Answer

Sn = (an² - a₁²) / 2d + (a₁ + an) / 2

= (210² - 2²) / 2·2 + (2 + 210) / 2

= 11130 #

匿名 · Answer

你哋啲題目咁深㗎！😔😔😔😡🤯🤯

傑 · Answer

項數＝(210-2)÷2+1=105
答案＝（210＋2)x105÷2=22260

耀聲 · Answer

2+4+6+8...........+208+210 = ?

Sol

A=2+4+6+…+206+208+210

A=210+208+206+…+6+4+2

2A=(2+210)+(4+208)+(6+2-6)+…+(206+6)+(208+4)+(210+2)

=212*(210/2)

=212*105

=22260

A=11130

or

項數=210/2=105

2+4+6+8...........+208+210

=(2+210)*105/2

=106*105

=11130

? · Answer

11130 is the answer
use畢氏定理

小玉 · Answer

(2+210)*105/2=11130 #

2+4+6+8...........+208+210 = ?

8 個解答