Tìm a: 0,75 : (0,2-0,125)<a<11,05
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\(\dfrac{x}{0,2}=\dfrac{y}{0,75}=\dfrac{z}{0,125}\)
\(\Rightarrow\dfrac{x^2}{\left(0,2\right)^2}=\dfrac{y^2}{\left(0,75\right)^2}=\dfrac{z^2}{\left(0,125\right)^2}=\dfrac{x^2+y^2+z^2}{\left(0,2\right)^2+\left(0,75\right)^2+\left(0,125\right)^2}=\dfrac{3956}{2^2.10^{-4}+75^2.10^{-4}+125^2.10^{-4}}=\dfrac{3956}{10^{-4}.\left(4+5625+15625\right)}=\dfrac{3956.10^4}{21254}\)
\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{3956.10^4}{21254}.0,2=\dfrac{7912.10^3}{21254}\\y=\dfrac{3956.10^4}{21254}.0,75=\dfrac{29670.10^3}{21254}\\z=\dfrac{3956.10^4}{21254}.0,125=\dfrac{4945.10^3}{21254}\end{matrix}\right.\)
Vậy \(M=x+y+z=\dfrac{7912.10^3+29670.10^3+4945.10^3}{21254}\)
\(M=\dfrac{\left(7912+29670+4945\right).10^3}{21254}=\dfrac{42527.10^3}{21254}\)
Ta thấy :
( 0,2 - 0,125 ) < a < 11,05
= 0,075 < a < 11,05
Vậy a = 1 ; 2 ; 3 ; 4 ; 5 ; 6 ; 7 ; 8 ; 9 ; 10 ; 11 .
\(a)101\times0,75-0,75\)
\(=0,75\times(101-1)\)
\(=0,75\times100=75\)
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`b)10:0,5+4:0,25+8:0,125`
\(=10\times2+4\times4+8\times8\)
\(=5\times4+4\times4+4\times16\)
\(=4\times(5+4+16)\)
\(=4\times25=100\)
a)101×0,75−0,75
=0,75\times(101-1)=0,75×(101−1)
=0,75\times100=75=0,75×100=75
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b)10:0,5+4:0,25+8:0,125b)10:0,5+4:0,25+8:0,125
=10\times2+4\times4+8\times8=10×2+4×4+8×8
=5\times4+4\times4+4\times16=5×4+4×4+4×16
=4\times(5+4+16)=4×(5+4+16)
=4\times25=100=4×25=100
a) x : 0,125 - x = 45
x * 1/8 - x = 45
x * (1/8 - 1) = 45
x * -7/8 = 45
x = -360/7
b) x : 0,2 + x * 5 - x : 0,25 = 54,75
x * 1/5 + x * 5 - x * 1/4 = 54,75
x * (1/5 + 5 - 1/4) = 54,75
x * 99/20 = 54,75
x = 365/33
<=>4a+0,5+5a+8a+a=200
<=>18a+0,5=200
<=>18a=199,5
<=>a=199,5:18=133/12
a) Ta có: \(\left(-2.5\cdot0.38\cdot0.4\right)-\left[0.125\cdot3.15\cdot\left(-8\right)\right]\)
\(=\left(-1\cdot0.38\right)-\left[-1\cdot3.15\right]\)
\(=-0.38+3.15\)
\(=\dfrac{277}{100}\)
b) Ta có: \(\left[\left(-20.83\right)\cdot0.2+\left(-9.17\right)\cdot0.2\right]:\left[2.47\cdot0.5-\left(-3.53\right)\cdot0.51\right]\)
\(=\dfrac{0.2\left(-20.83-9.17\right)}{3.0353}\)
\(=\dfrac{0.2\cdot\left(-30\right)}{3.0353}=\dfrac{-60000}{30353}\)
0,75/(0,2-0,125)<a<11,05
10<a<11,05(tính theo biểu thức bên trái ra 10)
Số tự nhiên a à 11
11