199 - 200 + 201 - 202 + 203 - 204 + 205 - 206 + 207

= ( 199 - 200 ) + ( 201 - 202 ) + ( 203 - 204 ) + ( 205 - 206 ) + 207

= ( -1 ) + ( -1 ) + ( -1 ) + ( -1 ) + 207

= -4 + 207

= 203

199 - 200 + 201 - 202 + 203 - 204 + 205 - 206 + 207 = 203 

199-200+201-202+203-204+205-206+207

=203

204 x 207 +200 / 207 x 205 -7

= 204 x 207 +207 - 7 / 207 x 205 -7

= 207 x ( 204 +1 ) -7 / 207 x 205 -7

= 207 x 205 -7 / 207 x 205 -7

= 1

tick nha !

a) 132 + 76 + 868 + 524 + 500

= (132 + 868) + (76 + 524) + 500

= 1000 + 600 + 500

= 2100

b) 200 - 201 + 202 - 203 + 204 - 205 + 206 - 207 + 208 - 209 + 210

= (200 + 210) + (-201 - 209) + (202 + 208) + (-203 - 207) + (204 + 206) - 205

= 410 - 410 + 410 - 410 + 410 - 205

=  0 + 0 + 205

= 205

trả lời nhamh vậy

gooddddddddddddddddddddddddddddddddddd

Sửa đề :

x + x + 1 + x + 2 + ... + x + 205 = 205

( x + x + ... + x ) + ( 1 + 2 + ... + 205 ) = 205

Số số hạng là : 

( 205 - 1 ) : 1 + 1 = 205 ( số )

Tổng là : 

( 205 + 1 ) . 205 : 2 = 21115

206x + 21115 = 205

206x = -20910

x = -101,5048544

x+(x+1)+(x+2)+....+204+205=205

=>x+(x+1)+(x+2)+....+204=0

mik nghĩ là sai đề bạn ơi

\(x+\left(x+1\right)+\left(x+2\right)+...+\left(x+205\right)=205\)

\(\left(x+x+x+...+x\right)+\left(1+2+3+....+205\right)\)

\(206x+\left[\left(205-1\right):1+1\right].\left(205+1\right):2\)

\(206x+2115=205\)

\(=>...\)

TL:

203+204+......+300

\(=\frac{\left(203+300\right).\left[\left(300-203\right)+1\right]}{2}\) 

\(=\frac{503.98}{2}\) 

\(=24647\) 

\(\)Đặt \(A=\frac{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}...+\frac{1}{205}}{\frac{204}{1}+\frac{203}{2}+\frac{202}{3}+...+\frac{1}{204}}=\frac{B}{C}\)

Biến đổi C:

\(C=\left(\frac{204}{1}+1\right)+\left(\frac{203}{2}+1\right)+\left(\frac{202}{3}+1\right)+...+\left(\frac{1}{204}+1\right)-204\)

\(=205+\frac{205}{2}+\frac{205}{3}+..+\frac{205}{204}+\frac{205}{205}-205\)

\(=205.\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{205}\right)\)

\(\Rightarrow A=\frac{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{205}}{205.\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{205}\right)}=\frac{1}{205}\)