TIM X BIET: 3^99 : (2.X-1)=3^97
tim X biet
3^99 : (2.x-1)^3 = 3^97
1) Tim A , biet :
(242 / 363 - 1616 / 2121) = 2 / 7 x A
2)Thuc hien phep tinh :
99 / 98 - 98 / 97 + 1 / 97 x 98
Tim x biet: x+1/98 + x+2/97 = x+3/96 + x+4/95
Ta có:
\(\frac{x+1}{98}+1+\frac{x+2}{97}+1=\frac{x+3}{96}+1+\frac{x+4}{95}+1\)
\(\frac{x+1}{98}+\frac{98}{98}+\frac{x+2}{97}+\frac{97}{97}=\frac{x+3}{96}+\frac{96}{96}+\frac{x+4}{95}+\frac{95}{95}\)
\(\frac{x+99}{98}+\frac{x+99}{97}=\frac{x+99}{96}+\frac{x+99}{95}\)
\(\frac{x+99}{98}+\frac{x+99}{97}-\frac{x+99}{96}-\frac{x+99}{95}=0\)
\(\left(x+99\right)\left(\frac{1}{98}+\frac{1}{97}-\frac{1}{96}-\frac{1}{95}\right)=0\)
Vì: \(\frac{1}{98}+\frac{1}{97}-\frac{1}{96}-\frac{1}{95}\ne0\)nên x+99=0
=> x=-99
tim x
x : 3 + 1 - 2 + 3 - 4 + 5 - 6 + .......... + 97 - 98 + 99 = 127
X = 3 x (1 + 3 + 5 +......+ 97 + 99) - (2 + 4 + 6 + ... + 96 + 98)
X = 3 x {(1 + 99) : 2 x [(99 - 1) : 2 + 1]} - {(2 +98) : 2 x [(98 - 2) : 2 + 1]}
X = 3 x 50 x 50 - 50 x 49
X = 3 x 50 x (50 - 49) = 150
Tim x
x+1/99+x+2/98+x+3/97+x+4/96=-4
4x + (1/99+2/98+3/97 + 4/96)=-4
4x=-4 - (1/99+2/98+3/97 + 4/96)
4x=
A=3 mu 100 - 3 mu 99 +3 mu 98 - 3 mu 97 + ... +3 mu 2 - 3 mu 1. Tim n biet 3 + 4A = 3 mu n
tim x biet (1+3+....+99)x=2+4+6+.....+100
(1+3+...+99)x = 2+4+6+100
2500x=2550
x=2550:2500
x= 1,02
Kẻ bí mật này, tớ tưởng 2+4+6+100=112 chứ?! Sao ra 2550 giỏi vậy! Đúng là ấm đầu thiệt rùi!
tim x cua N biet 1+3+5+..............................................+99= (x-2)^2
Số các số hạng là:
(99-1):2+1=50(số)
Tổng là:(1+99)x50:2=2500
Ta có:2500=50^2
=>x-2=50
x=2+50
x-52
Vậy x=52
Trước tiên ta phải tìm kết quả của tổng đó .
Số số hạng là : ( 99-1 ) : 2 + 1 = 50
Tổng trên có kết quả là: ( 99+1 ) . 50 : 2 = 2500
<=> (x-2)2 = 2500
x-2 = 50 ( 2500 = 25.25 )
x = 50 + 2
x = 52
bạn sửa lại ở phần x-2 = 50 ( 2500 = 50.50 ) nhé
\(\frac{x+1}{99}+\frac{x+2}{98}+\frac{x+3}{97}+\frac{x+4}{96}=-4\)
tim x
\(\frac{x+1}{99}+\frac{x+2}{98}+\frac{x+3}{97}+\frac{x+4}{96}=-4\)
\(\Rightarrow\left(\frac{x+1}{99}+1\right)+\left(\frac{x+2}{98}+1\right)+\left(\frac{x+3}{97}+1\right)+\left(\frac{x+4}{96}+1\right)=-4+4\)
\(\Rightarrow\frac{x+100}{99}+\frac{x+100}{98}+\frac{x+100}{97}+\frac{x+100}{96}=0\)
\(\Rightarrow\left(x+100\right).\left(\frac{1}{99}+\frac{1}{98}+\frac{1}{97}+\frac{1}{96}\right)=0\)
Mà \(\frac{1}{99}+\frac{1}{98}+\frac{1}{97}+\frac{1}{96}>0\)
\(\Rightarrow x+100=0\)
\(\Rightarrow x=0-100\)
\(\Rightarrow x=-100\)
Chúc bạn học tốt !!!!
\(\frac{x+1}{99}+\frac{x+2}{98}+\frac{x+3}{97}+\frac{x+4}{96}=-4\)
\(\Leftrightarrow\left(\frac{x+1}{99}+1\right)+\left(\frac{x+2}{98}+1\right)+\left(\frac{x+3}{97}+1\right)+\left(\frac{x+4}{96}+1\right)=0\)
\(\Leftrightarrow\frac{x+100}{99}+\frac{x+100}{98}+\frac{x+100}{97}+\frac{x+100}{96}=0\)
\(\Leftrightarrow\left(x+100\right)\left(\frac{1}{99}+\frac{1}{98}+\frac{1}{97}+\frac{1}{96}\right)=0\)
\(\Leftrightarrow x+100=0\)
\(\Leftrightarrow x=-100\)
Vậy...
\(\Rightarrow\left(\frac{x+1}{99}+1\right)+\left(\frac{x+2}{98}+1\right)+\left(\frac{x+3}{97}+1\right)+\left(\frac{x+4}{96}+1\right)=-4+1+1+1+1\)
\(\Rightarrow\frac{x+100}{99}+\frac{x+100}{98}+\frac{x+100}{97}+\frac{x+100}{96}=0\)
\(\Rightarrow\left(x+100\right).\left(\frac{1}{99}+\frac{1}{98}+\frac{1}{97}+\frac{1}{96}\right)=0\)
Vì 1/99+1/98+1/97+1/96>0
\(\Rightarrow x+100=0\Rightarrow x=-100\)