\(\left(y+1\right)+\left(y+2\right)+\left(y+3\right)+...+\left(y+99\right)=2550\)
Có \(\left(99-1\right):1+1=99\)cặp
\(\left(y+y+y+...+y\right)+\left(1+2+3+...+99\right)=2550\)
\(99y+\left[\left(99+1\right)\times99:2\right]=2550\)
\(99y+4590=2550\)
\(99y=2550-4590\)
\(99y=-2040\)
\(y=\frac{-680}{33}\)
Đề hình như sai bạn ơi
#)Giải :
\(\left(y+1\right)+\left(y+2\right)+\left(y+3\right)+...+\left(y+99\right)=2550\)
\(\Rightarrow\left(y+y+y+...+y\right)+\left(1+2+3+...+99\right)=2550\)
\(\Rightarrow99y+\frac{\left(99+1\right).99}{2}=2550\)
\(\Rightarrow99y+4950=2550\)
\(\Leftrightarrow99y=-2400\)
\(\Leftrightarrow y=-24,2424242424.................\approx-24,24\)
P/s : Có j đó sai sai :v đề lỗi ak ?
(y+1)+(y+2)+(y+3)+...+(y+99)=2550
<=> \(99y+\frac{\left(99+1\right).99}{2}=2550\)
<=>\(99y+4590=2550\Leftrightarrow99y=\frac{85}{153}\)
<=>\(y=\frac{85}{15147}=\frac{5}{891}\)
( y + 1) + ( y + 2 ) + ( y + 3) + ...+ (y + 99) = 2550
= ( y + y + ..+ y ) + ( 1 + 2 + 3 + ...+ 99 )
99 SH y Dãy TNLT
= 99y + \(\frac{\left(1+99\right).99}{2}\)= 2550
=> 99y + 4950 = 2550
99y = 2550 - 4950
99y = -2400
=> y = -2400 : 99 = -24, 2424.... ?
#)Thắc mắc :
Sao bn nào cg nhầm ( 99 + 1 ) x 99 : 2 = 4590 thế nhỉ ??
99 + 1 = 100 x 99 = 9900 : 2 = 4950 mak ???
( y + 1 ) + ( y + 2 ) + ... + ( y + 99 ) = 2550
( y + y + ... + y ) + ( 1 + 2 + ... + 99 ) = 2550
99y + ( 99 + 1 ) . 99 : 2 = 2550
99y + 4950 = 2550
mà 4950 > 2550 => y không có giá trị
(y + 1) + ( y + 2) + ... + (y + 99) = 2550
=> (y + y + .... + y) + (1 + 2 + 3 +... + 99) = 2550 (99 số hạng y)
=> 99 \(\times\) y + 99 x 100 : 2 = 2550
=> 99 \(\times\) y + 99 x 50 = 2550
=> 99 \(\times\)y + 4950 = 2550
=> 99 x y = 2550 - 4950
=> 99 x y = - 2400
=> y = - 2400 : 99
=> y = - 2400/99
Từ y + 1 -> y + 99 có số số hạng là: (99 - 1): 1 + 1 = 99 (số)
\(\Rightarrow y+1+y+2+...+y+99=99y+\left(1+2+...+99\right)=2550\)
\(\Rightarrow99y+\frac{\left(1+99\right).99}{2}=2550\)
\(\Rightarrow99y+4950=2550\)
\(\Rightarrow99y=-2400\)
\(\Rightarrow y=\frac{-2400}{99}\)
