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Bài 1:
\(\left(-0,125\right)\times7,9\times80\)
\(=\left(-0,9875\right)\times80\)
\(=79.\)
\(\left(0,125\right)\times1\times0,25\times8\times\left(-4\right)\)
\(=0,125\times0,25\times8\times\left(-4\right)\)
\(=0,03125\times8\times\left(-4\right)\)
\(=0,25\times\left(-4\right)\)
\(=\left(-1\right).\)
Bài 2:
\(x+\frac{8}{3}^2=\frac{1}{9}\)
\(x+16=\frac{1}{9}\)
\(x=\frac{1}{9}-16.MSC=9\)
\(x=\frac{1}{9}-\frac{144}{9}\)
\(x=\frac{-143}{9}.\)
a) \(2,5:2,7=x:\frac{3}{5}\)
\(\Rightarrow\frac{5}{2}:\frac{27}{10}=x.\frac{5}{3}\)
\(\Rightarrow\frac{5}{2}.\frac{10}{27}=\frac{5x}{3}\)
\(\Rightarrow\frac{25}{27}=\frac{5x}{3}\)
\(\Rightarrow5x=\frac{25.3}{27}=\frac{75}{27}=\frac{25}{9}\)
\(\Rightarrow x=\frac{25}{9}:5=\frac{25}{9}.\frac{1}{5}=\frac{5}{9}\)
b) \(\frac{19}{5}:\frac{608}{15}=0,25:x\)
\(\Rightarrow\frac{19}{5}.\frac{15}{608}=\frac{1}{4}:x\)
\(\Rightarrow\frac{3}{32}=\frac{1}{4}:x\)
\(\Rightarrow x=\frac{1}{4}:\frac{3}{32}=\frac{1}{4}.\frac{32}{3}=\frac{8}{3}\)
c/ \(\frac{8}{3}:x=\frac{16}{9}:0,2\)
\(\Rightarrow\frac{8}{3}:x=\frac{16}{9}:\frac{1}{5}=\frac{16}{9}.5=\frac{80}{9}\)
\(\Rightarrow x=\frac{8}{3}:\frac{80}{9}=\frac{8}{3}.\frac{9}{80}=\frac{3}{10}\)
\(1,\\ a,=\left(\dfrac{1}{4}\right)^3\cdot32=\dfrac{1}{64}\cdot32=\dfrac{1}{2}\\ b,=\left(\dfrac{1}{8}\right)^3\cdot512=\dfrac{1}{512}\cdot512=1\\ c,=\dfrac{2^6\cdot2^{10}}{2^{20}}=\dfrac{1}{2^4}=\dfrac{1}{16}\\ d,=\dfrac{3^{44}\cdot3^{17}}{3^{30}\cdot3^{30}}=3\\ 2,\\ a,A=\left|x-\dfrac{3}{4}\right|\ge0\\ A_{min}=0\Leftrightarrow x=\dfrac{3}{4}\\ b,B=1,5+\left|2-x\right|\ge1,5\\ A_{min}=1,5\Leftrightarrow x=2\\ c,A=\left|2x-\dfrac{1}{3}\right|+107\ge107\\ A_{min}=107\Leftrightarrow2x=\dfrac{1}{3}\Leftrightarrow x=\dfrac{1}{6}\)
\(d,M=5\left|1-4x\right|-1\ge-1\\ M_{min}=-1\Leftrightarrow4x=1\Leftrightarrow x=\dfrac{1}{4}\\ 3,\\ a,C=-\left|x-2\right|\le0\\ C_{max}=0\Leftrightarrow x=2\\ b,D=1-\left|2x-3\right|\le1\\ D_{max}=1\Leftrightarrow x=\dfrac{3}{2}\\ c,D=-\left|x+\dfrac{5}{2}\right|\le0\\ D_{max}=0\Leftrightarrow x=-\dfrac{5}{2}\)
a) (0.25)^3*32
= (0.5)^5*0.5*2^5
=1^5*0.5
=1*0.5
=0.5
b)(-0.125)^3*80^4
=(-0.125)^3*80^3*80
=(-0.125*80)^3*80
=(-10)^3
=-1000*80
=-80000
c) 8^2*4^5/2^20
=(23)2*(22)5*2^20
=2^6*2^10*2^20
=2^36
d)81^11*3^17/27^10*9^15
=((34)11*3^17)/(33)10*(32)15
=(3^44*3^17)/(3^30*3^30)
=3^61/3^60
=3
Bài b) dòng thứ 3 từ dưới đếm lên, phải là, (-10)^3*80 nha, gấp quá mình ghi nhầm ;)
a, 30,24 + 30,24 + 30,24 + 30,24 x 7 - 30,24 : 0,1
= 30,24 x 3 + 30,24 x 7 - 30,24 : 0,1
= 30,24 x 10 - 30,24 : 0,1
= 30,24 x 10 - 30,24 x 10
= 0
b, 2 giờ 30 phút x 8 + 2,5 giờ x 3 - 150 phút
= 2,5 giờ x 8 + 2,5 giờ x 3 - 150 phút
= 2,5 giờ x 8 + 2,5 giờ x 3 - 2,5 giờ
= 2,5 giờ x 10
= 25 giờ
c, 1/2 : 0,5 - 1/4 : 0,25 + 1/8 : 0,125 - 1/10 : 0,1
= 1/2 x 2 + 1/4 x 4 + 1/8 x 8 - 1/10 x 10
= 1 + 1 + 1 - 1
= 2
\(\dfrac{9}{19}-1,251+\dfrac{10}{19}+1,251=\dfrac{19}{19}-1,251+1,252=1\)
\(-8.24,7.0,125=-8.24,7.\dfrac{1}{8}=-24,7\)
\(0,25.\dfrac{7}{15}-\dfrac{1}{4}\left(-\dfrac{8}{15}\right)+0,25=\dfrac{1}{4}.\dfrac{7}{15}-\dfrac{1}{4}\left(-\dfrac{8}{15}\right)+\dfrac{1}{4}=\dfrac{1}{4}\left(\dfrac{7}{15}+\dfrac{8}{15}+1\right)=\dfrac{1}{4}.2=\dfrac{1}{2}\)
`9/19 - 1,251 + 1,251 + 10/19`
`= (9/19 + 10/19) + (1,251 - 1,251)`
`= 1 + 0`
`= 1`
`(-8) × 24,7 × 0,125`
`= [(-8) × 0,125] × 24,7`
`= (-1) × 24,7`
`= (-24,7)`
`0,25 × 7/15 - 1/4 × (-8/15) + 0,25 `
`= 0,25 × 7/15 - 0,25 × (-8/15) + 0,25 × 1`
`= 0,25 × [7/15 -(-8/15) + 1]`
`= 0,25 × [7/15 + 8/15 + 1]`
`= 0,25 × 2`
`= 0,5`