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5,25 x 4,1 + (-2,05) x 16,4 + 2,625 x 8,2
= 21,525 + (-33,62) + 21,525
= (-12,095) +21,525 = 9,43
Dài wa nên mk chỉ ghi đáp án thui nha
a, x=1
b,x=66
c,x=4
d,x=5/3
e,x=17/25
a) \(\left(\dfrac{1}{2}+\dfrac{1}{6}+...+\dfrac{1}{90}\right)\cdot100-\left[\dfrac{5}{2}:\left(x+\dfrac{206}{100}\right)\right]:\dfrac{1}{2}=89\)
\(\Rightarrow\left(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+...+\dfrac{1}{9\cdot10}\right)\cdot100-\left[\dfrac{5}{2}:\left(x+\dfrac{103}{50}\right)\right]:\dfrac{1}{2}=89\)
\(\Rightarrow\left(1-\dfrac{1}{2}+\dfrac{1}{2}-...+\dfrac{1}{9}-\dfrac{1}{10}\right)\cdot100-\left[\dfrac{5}{2}:\left(x+\dfrac{103}{50}\right)\right]:\dfrac{1}{2}=89\)
\(\Rightarrow\left(1-\dfrac{1}{10}\right)\cdot100-\left[\dfrac{5}{2}:\left(x+\dfrac{103}{50}\right)\right]:\dfrac{1}{2}=89\)
\(\Rightarrow\dfrac{9}{10}\cdot100-\left[\dfrac{5}{2}:\left(x+\dfrac{103}{50}\right)\right]:\dfrac{1}{2}=89\)
\(\Rightarrow90-\left[\dfrac{5}{2}:\left(x+\dfrac{103}{50}\right)\right]:\dfrac{1}{2}=89\)
\(\Rightarrow\dfrac{5}{2}:\left(x+\dfrac{103}{50}\right)=90-89\)
\(\Rightarrow\dfrac{5}{2}:\left(x+\dfrac{103}{50}\right)=1\)
\(\Rightarrow x+\dfrac{103}{50}=\dfrac{5}{2}\)
\(\Rightarrow x=\dfrac{11}{25}\)
b) \(x\cdot9,85+x\cdot0,15=0,1\)
\(\Rightarrow x\cdot\left(9,85+0,15\right)=0,1\)
\(\Rightarrow x\cdot10=0,1\)
\(\Rightarrow x=\dfrac{0,1}{10}\)
\(\Rightarrow x=0,01\)
c) \(\dfrac{2}{5}+2022x=\dfrac{4}{10}\)
\(\Rightarrow\dfrac{2}{5}+2022x=\dfrac{2}{5}\)
\(\Rightarrow2022x=\dfrac{2}{5}-\dfrac{2}{5}\)
\(\Rightarrow2022x=0\)
\(\Rightarrow x=\dfrac{0}{2022}\)
\(\Rightarrow x=0\)
a) \(\left(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+...+\dfrac{1}{90}\right).100-\left[\dfrac{5}{2}:\left(x+\dfrac{206}{100}\right)\right]:\dfrac{1}{2}=89\left(1\right)\)
Ta có :
\(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+...+\dfrac{1}{90}\)
\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{9}-\dfrac{1}{10}\)
\(=1-\dfrac{1}{10}=\dfrac{9}{10}\)
\(\left(1\right)\Rightarrow\dfrac{9}{10}.100-\left[\dfrac{5}{2}:\left(x+\dfrac{206}{100}\right)\right]:\dfrac{1}{2}=89\)
\(\Rightarrow90-\left[\dfrac{5}{2}:\left(x+\dfrac{206}{100}\right)\right].2=89\)
\(\Rightarrow\left[\dfrac{5}{2}:\left(x+\dfrac{206}{100}\right)\right].2=90-89\)
\(\Rightarrow\dfrac{5}{2}:\left(x+\dfrac{206}{100}\right)=\dfrac{1}{2}\)
\(\Rightarrow x+\dfrac{206}{100}=\dfrac{5}{2}:\dfrac{1}{2}\)
\(\Rightarrow x+\dfrac{103}{50}=\dfrac{5}{2}.\dfrac{2}{1}\)
\(\Rightarrow x+\dfrac{103}{50}=5\)
\(\Rightarrow x=5-\dfrac{103}{50}\)
\(\Rightarrow x=\dfrac{250}{50}-\dfrac{103}{50}\)
\(\Rightarrow x=\dfrac{147}{50}\)
Tính phải k nhỉ?
`1)`
`2x + 3x + 5x`
`= (2 + 3 + 5)x`
`= 10x`
`2)`
`2.x - x + 3.x`
`= (2 - 1 + 3)x`
`= 4x`
`3)`
`9.x - 3 - 3.x`
`= (9 - 3)x - 3`
`= 6x - 3`
`4)`
Thiếu dấu, bạn bổ sung thêm
`5)`
`x - 0,2x - 0,1x`
`= (1 - 0,2 - 0,1)x`
`=0,7x`
`6)`
\(\dfrac{7}{2}x-\dfrac{1}{2}x=\left(\dfrac{7}{2}-\dfrac{1}{2}\right)x=3x\)
a) 8,2x + 1,8x = 0,3
x(8,2 + 1,8) = 0,3
10x = 0,3
x = 0,3 : 10
x = 0,03
b) 2448 : [119 - (x - 6)] = 24
119 - (x - 6) = 2448 : 24
119 - (x - 6) = 102
x - 6 = 119 - 102
x - 6 = 17
x = 17 + 6
x = 23
a, 8,2.x+1,8.x = 0,3
x.(8,2+1,8) = 0,3
x.10 = 0,3
x = 0,3:10
x = 3/100
b, 2448 : [119-(x-6)] = 24
119-(x-6) = 2448:24
119-(x-6) = 102
x-6 = 119-102
x-6 = 17
x = 17+6
x =23
2:
a: =>x=1/2+1/6=3/6+1/6=4/6=2/3
b: =>x+3,5=7,8-6,3=1,5
=>x=1,5-3,5=-2
c: =>(35-x)/-105=1/5
=>35-x=-21
=>x=56
1
c hình như tính bình thường thôi:v
d
= 1,75 : 5 + 2,5 . (16 – 4 . 4,1)
= 1,75 : 5 + 2,5 . (16 – 16,4)
= 1,75 : 5 + 2,5 . (−0,4)
= 0,35 − 1
= −0,65.
2
a
\(\Rightarrow x=\dfrac{1}{2}+\dfrac{1}{6}=\dfrac{3}{6}+\dfrac{1}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)
b
\(\Rightarrow x+\dfrac{35}{10}=\dfrac{78}{10}-\dfrac{63}{5}:2\\ \Rightarrow x+\dfrac{35}{10}=\dfrac{78}{10}-\dfrac{63}{10}=\dfrac{15}{10}\\ \Rightarrow x=\dfrac{15}{10}-\dfrac{35}{10}=-2\)
c không rõ đề:v
`1,2 xx 0,1 = 0,12 =3/25 `
`4,6 xx 0,001 =23/5000`
`781,5 xx 0,01 =7,815 = 1563/200`
`15,4 xx 0,01 =0,154 =77/500`
`45,82 xx 0,1 =4,582=2291/500`
`15632 xx 0,001 =15,632 = 1954/125`
bằng 820 nha