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Quy đồng : \(\frac{-33}{134}=\frac{-33.203}{134.203}=\frac{-6699}{134.203}\)
\(\frac{-51}{203}=\frac{-52.134}{203.134}=\frac{-6834}{134.203}\)
So sánh tử ta được -6699>-6834
Nên: \(\frac{-6699}{134.203}>\frac{-6834}{134.203}\) ( Với hai số cùng mẫu, tử càng lớn thì phân số càng lớn)
Vậy \(\frac{33}{-134}>\frac{-51}{203}\)
Ta so sánh \(\frac{33}{134}\)với\(\frac{51}{203}\)
Ta có:
\(\frac{33}{134}< \frac{33}{132}=\frac{1}{4}\)
\(\frac{51}{203}>\frac{51}{204}=\frac{1}{4}\)
\(\Rightarrow\frac{33}{134}< \frac{1}{4}< \frac{51}{203}\)
\(\Rightarrow\frac{33}{-134}>\frac{1}{4}>\frac{-51}{203}\)
\(.\Rightarrow\frac{33}{-134}>\frac{-51}{203}\)
a) \(25.\left(-7\right).4=\left(25.4\right).\left(-7\right)=100.\left(-7\right)=-700\)
b) \(33.\left(17-5\right)-17.\left(33-5\right)=33.17-33.5-17.33+17.5=5.\left(17-33\right)\)\(=5.\left(-16\right)=-80\)
\(-\dfrac{3}{8}-\left(-\dfrac{3}{24}\right)\)
\(=-\dfrac{3}{8}+\dfrac{3}{24}\)
\(=-\dfrac{9}{24}+\dfrac{3}{24}\)
\(=\dfrac{-9+3}{24}\)
\(=-\dfrac{6}{24}\)
\(=-\dfrac{1}{4}\)
Chào bạn, bạn hãy theo dõi bài giải của mình nhé!
\(\frac{2}{3}-\left(-\frac{1}{4}\right)+\frac{3}{5}-\frac{7}{45}-\left(-\frac{7}{9}\right)+\frac{1}{12}+\frac{1}{39}\)
\(=\frac{2}{3}+\frac{1}{4}+\frac{3}{5}-\frac{7}{45}+\frac{7}{9}+\frac{1}{12}+\frac{1}{39}\)
\(=\left(\frac{2}{3}+\frac{1}{4}+\frac{1}{12}\right)+\left(\frac{7}{9}+\frac{3}{5}-\frac{7}{45}\right)+\frac{1}{39}\)
\(=\left(\frac{8}{12}+\frac{3}{12}+\frac{1}{12}\right)+\left(\frac{35}{45}+\frac{27}{45}-\frac{7}{45}\right)+\frac{1}{39}\)
\(=\frac{12}{12}+\frac{55}{45}+\frac{1}{39}=1+\frac{11}{9}+\frac{1}{39}=\frac{351}{351}+\frac{429}{351}+\frac{9}{351}=\frac{789}{351}\)
2 3 − ( − 1 4 ) + 3 5 − 7 45 − ( − 7 9 ) + 1 12 + 1 39 = 2 3 + 1 4 + 3 5 − 7 45 + 7 9 + 1 12 + 1 39 = ( 2 3 + 1 4 + 1 12 ) + ( 7 9 + 3 5 − 7 45 ) + 1 39 = ( 8 12 + 3 12 + 1 12 ) + ( 35 45 + 27 45 − 7 45 ) + 1 39 = 12 12 + 55 45 + 1 39 = 1 + 11 9 + 1 39 = 351 351 + 429 351 + 9 351 = 789 351
7 3 + − 5 6 + − 2 3 = 7 3 + − 5 6 + − 2 3 = 7 3 + − 2 3 + − 5 6 = 5 3 + − 5 6 = 10 + − 5 6 = 5 6
4 3 − − 11 6 − 2 9 + 5 3 = 4 3 + 11 6 + 2 9 + 5 3 = 4 3 + 11 6 + 2 9 + 5 3 = 24 + 33 + 4 + 33 18 = 91 18
5 − 7 − − 5 − 7 + 4 3 = − 5 7 − 5 7 + 4 3 = − 10 7 + 4 3 = − 30 + 28 21 = − 2 21
a.A=-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72=-151/180
Vậy A=151/180
b.B=0,5+0,4+1/3+1/6+5/7-4/35=2
Vậy B=2
( chú ý vì x/5 = y/7 = z/3 =>x;y;z cùng dấu )
x/5 = y/7 = z/3 =>(x/5)^2= (y/7)^2 = (z/3)^2 hay x^2/25 = y^2/49 =z^2 /9
x^2/25 = y^2/49 =z^2 /9 = (x^2 + y^2 - z^2) /(25+49 -9)=585/65 =9=3^2
=> (x/5)^2=3^2 =>x/5 =+-3 =>x=+-15
(y/7)^2=3^2 =>y/7 =+-3 =>y=+-21
(z/3)^2 =3^2 =>z/3 =+-3 =>z=+-9
vậy có 2 cặp (x;y;z) là: (15;21;9) và (-15;-21;-9)
\(B=2^{2016}-2^{2015}+...+2^2-2^1+1\)
=>\(2B=2^{2017}-2^{2016}+...+2^3-2^2+2\)
=>\(2B+B=2^{2017}-2^{2016}+...+2^3-2^2+2+2^{2016}-2^{2015}+...+2^2-2+1\)
=>\(3B=2^{2017}+1\)
=>\(B=\dfrac{2^{2017}+1}{3}\)
Lời giải:
$B=2^{2016}-2^{2015}+2^{2014}-2^{2013}+...+2^2-2^1+2^0$
$2B=2^{2017}-2^{2016}+2^{2015}-2^{2014}+...+2^3-2^2+2^1$
$\Rightarrow B+2B=2^{2017}+2^0=2^{2017}+1$
$\Rightarrow 3B=2^{2017}+1$
$\Rightarrow B=\frac{2^{2017}+1}{3}$