Tính
a) 9/8 - 8/9 = 8/25 + 1/4 - 5/16 + 19/25 - 1/9 + 2/25 - 1/81
b) -1/3 + 4/5 - 8/35 + -2/9 - 1/135 + -4/9 + 3/7
Các bn giải giúp mình nha chiều nay mk phải đi học rùi
Làm chi tiết nha
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\(A=\dfrac{9}{8}-\dfrac{8}{9}+\dfrac{3}{24}+\dfrac{1}{4}-\dfrac{5}{16}+\dfrac{19}{25}-\dfrac{1}{9}+\dfrac{2}{25}-\dfrac{1}{81}\)
\(=\dfrac{9}{8}+\dfrac{1}{4}-\dfrac{5}{16}+\dfrac{1}{8}-\dfrac{8}{9}-\dfrac{1}{9}-\dfrac{1}{81}+\dfrac{19}{25}+\dfrac{2}{25}\)
\(=\dfrac{10}{8}+\dfrac{1}{4}-\dfrac{5}{16}-1-\dfrac{1}{81}+\dfrac{21}{25}\)
\(=\dfrac{20+4-5}{16}-\dfrac{82}{81}+\dfrac{21}{25}\)
\(=\dfrac{19}{16}-\dfrac{82}{81}+\dfrac{21}{25}\)
\(=\dfrac{32891}{16\cdot81\cdot25}\)
b: \(B=-\dfrac{1}{3}-\dfrac{8}{35}-\dfrac{2}{9}-\dfrac{1}{35}+\dfrac{4}{5}-\dfrac{4}{9}+\dfrac{3}{7}\)
\(=\dfrac{-1}{3}-\dfrac{2}{9}-\dfrac{4}{9}-\dfrac{8}{35}-\dfrac{1}{35}+\dfrac{4}{5}+\dfrac{3}{7}\)
\(=\dfrac{-3-2-4}{9}+\dfrac{-9}{35}+\dfrac{28+15}{35}\)
\(=-1+\dfrac{-9+43}{35}=-1+\dfrac{34}{35}=-\dfrac{1}{35}\)
\(A=\frac{9}{8}-\frac{8}{9}+\frac{3}{25}+\frac{1}{4}-\frac{5}{16}+\frac{19}{25}-\frac{1}{9}+\frac{2}{25}-\frac{1}{81}\)
\(A=\left(\frac{9}{8}+\frac{1}{4}-\frac{5}{16}\right)-\left(\frac{8}{9}+\frac{1}{9}-\frac{1}{81}\right)+\left(\frac{3}{25}+\frac{19}{25}+\frac{2}{25}\right)\)
\(A=\frac{17}{16}-\frac{80}{81}+\frac{24}{25}\)
\(A=\frac{33529}{32400}\)
\(2.x=\frac{1+2+3+...+9}{1-2+3-4+5-6+7-8+9}+\frac{25.150-60.5+20.75}{1+2+3+...+99}\)
\(2.x=\frac{\left(9+1\right).9:2}{\left(1-2\right)+\left(3-4\right)+\left(5-6\right)+\left(7-8\right)+9}+\frac{2.3.5^2.\left(5^2-2+2.5\right)}{\left(1+99\right).99:2}\)
\(2.x=\frac{45}{\left(-1\right)+\left(-1\right)+\left(-1\right)+\left(-1\right)+9}+\frac{2.3.5^2.33}{100.99.\frac{1}{2}}\)
\(2x=\frac{45}{5}+\frac{50.99}{50.2.99.\frac{1}{2}}=9+\frac{1}{2.\frac{1}{2}}=9+1=10\)
=> 2x = 10
x = 5
a: \(=\dfrac{-8}{9}-\dfrac{6}{5}+\dfrac{8}{9}=-\dfrac{6}{5}\)
c: \(=\dfrac{2}{3}-\dfrac{1}{3}=\dfrac{1}{3}\)
a)
`9/2-3`
`=9/2-6/2`
`=3/2`
b)
`8/5xx25/12`
`=10/3`
c)
`4:3/7`
`=4xx7/3`
`=28/3`
a: =-5/9-4/9+8/15+7/15-2/11=-2/11
b: =10/17+7/17-5/13-8/13+11/25
=11/25
c: =(9/12-2/12)*3/2=7/12*3/2=21/24=7/8
d: =(31/10-25/10)*3-2
=3/5*3-2
=9/5-2
=-1/5
Tui cux k bt nữa tui tính rồi mà tinhs mãi k ra
Bà bt ln chưa chỉ tôi vs