98-50=?
50 x 98 + 50 +50 = ?
50 x 98 + 50 + 50
= 4900 + ( 50 + 50 )
= 4900 + 100
= 5000
Chúc bạn học tốt
Tích nha
\(50\cdot98+50+50=50\cdot\left(98+1+1\right)=50\cdot100=5000\)
1/2+1/12+1/30+...+1/9120+1/9506+1/9900. / 50-50/51-51/52-...-97/98-98/99-99/100
Tính nhẩm:
a) 98 + 47
b) 121 - 98
c) 16 . 50
d) 1300 : 50
a 98 + 47 = 145
121 - 98 = 23
16 . 50 = 800
1300 : 50 = 26
số đó là
125
23
800
26
ủng hộ
mình nhé
1*99+2*98+3*97+...+51*50+50*50
1,Giải phương trình:
\(\frac{x+1}{99}\)+\(\frac{x+2}{98}\)+...+\(\frac{x+50}{50}\)+50=0
Ta có: \(\dfrac{x+1}{99}+\dfrac{x+2}{98}+...+\dfrac{x+50}{50}+50=0\)
\(\Leftrightarrow\dfrac{x+1}{99}+1+\dfrac{x+2}{98}+1+...+\dfrac{x+50}{50}+1=0\)
\(\Leftrightarrow\dfrac{x+100}{99}+\dfrac{x+100}{98}+...+\dfrac{x+100}{50}=0\)
\(\Leftrightarrow\left(x+100\right)\left(\dfrac{1}{99}+\dfrac{1}{98}+...+\dfrac{1}{50}\right)=0\)
mà \(\dfrac{1}{99}+\dfrac{1}{98}+...+\dfrac{1}{50}>0\)
nên x+100=0
hay x=-100
Vậy: S={-100}
\(\dfrac{x+1}{99}+\dfrac{x+2}{98}+...+\dfrac{x+50}{50}+50=0\)
\(\Leftrightarrow\left(\dfrac{x+1}{99}+1\right)+\left(\dfrac{x+2}{98}+1\right)+\left(\dfrac{x+3}{97}+1\right)+...+\left(\dfrac{x+50}{50}+1\right)=0\)
\(\Leftrightarrow\dfrac{x+100}{99}+\dfrac{x+100}{98}+...+\dfrac{x+100}{50}=0\)
\(\Leftrightarrow\left(x+100\right).\left(\dfrac{1}{99}+\dfrac{1}{98}+\dfrac{1}{97}+...+\dfrac{1}{50}\right)=0\)
\(\Leftrightarrow x+100=0\) (vì \(\dfrac{1}{99}+\dfrac{1}{98}+\dfrac{1}{97}+...+\dfrac{1}{50}>0\) )
\(\Leftrightarrow x=-100\)
tính A=1*99+2*98+3*97+...+49*51+50*50
tinh tong s=1*100+2*99+3*98+..+49*51+50*50
Giúp mình với
1*99+2*98+3*97+...+49.51+50*50
((1002+12)/(100*1))+((992+22)/(99*2))+((982+32)/(98*3))+...+((512+502)/(51*50))