Bài 4: Thực hiện phép tính a) 100: 25 + 7.9 b) 15.23 + 4.26 – 5.12 c) 151 – 2 91: 288 + 12 .33 d) 7 9 : 77 – 3 2 + 23 .25 e) 84: 4 + 39 : 37 + 50
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\(j,\dfrac{2}{5.7}+\dfrac{2}{7.9}+...+\dfrac{2}{53.55}=\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+...+\dfrac{1}{53}-\dfrac{1}{55}=\dfrac{1}{5}-\dfrac{1}{55}=\dfrac{11}{55}-\dfrac{1}{55}=\dfrac{10}{55}=\dfrac{2}{11}\\ k,\dfrac{1}{2}.\dfrac{2}{3}.\dfrac{3}{4}.\dfrac{4}{5}...\dfrac{99}{100}=\dfrac{1}{100}.\dfrac{2}{2}.\dfrac{3}{3}...\dfrac{99}{99}=\dfrac{1}{100}.1.1...1=\dfrac{1}{100}\)
a) 225 - ( -45 ) - 100
=225+45-100
=270-100
=170
b) | - 25 | + | 25 | - ( - 50 )
=25+25+50
=50+50
=100
c) 25 - 5. [( -4 )2 + 4 ] . ( -1)5
=25-5.[(-16)+4].(-5)
=25-5.(-12).(-5)
=25-(-60).(-5)
=25-300
=-275
tick nha
a)Ta có:
\(A=4\frac{25}{16}+25\left(\frac{9}{16}:\frac{125}{64}\right):\frac{-27}{8}\)
\(\Rightarrow A=\frac{89}{16}+25.\frac{36}{125}:\frac{-27}{8}\)
\(\Rightarrow A=\frac{89}{16}+\frac{36}{5}:\frac{-27}{8}\)
\(\Rightarrow A=\frac{89}{16}+\frac{-32}{15}\)
\(\Rightarrow A=\frac{823}{240}\)
Vậy A=.....
b)Ta có:
\(C=\frac{2^3}{3.5}+\frac{2^3}{5.7}+\frac{2^3}{7.9}+...+\frac{2^3}{101.103}\)
\(\Rightarrow C=\frac{2^2.2}{3.5}+\frac{2^2.2}{5.7}+\frac{2^2.2}{7.9}+...+\frac{2^2.2}{101.103}\)
\(\Rightarrow C=2^2\left(\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+...+\frac{2}{101.103}\right)\)
\(\Rightarrow C=4\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+....+\frac{1}{101}-\frac{1}{103}\right)\)
\(\Rightarrow C=4\left(\frac{1}{3}-\frac{1}{103}\right)\)
\(\Rightarrow C=4.\frac{100}{309}\)
\(\Rightarrow C=\frac{400}{309}\)
Vậy C=.....
\(160-\left(2^3.5^2-6.25\right)\)
\(=160-\left(8.25-6.25\right)\)
\(=160-\left[\left(8-6\right).25\right]\)
\(=160-\left[2.25\right]\)
\(=160-50\)
\(=110\)
~ Hok tốt ~
a,5/9+(-3/5) +( -5/9)
=5/9+(-5/9)+(-3/5)
=0+(-3/5)
=-3/5
b, b,-3/7. 2/11- (-3/7).9/11
=-3/7.(2/11-9/11)
=-3/7.(-7/11)
=3/11
c,,2/3 + 5/6 : 5 - 1/18 . (-3)
=2/3+(1/6-(-1/6))
=2/3+1/3
=3/3
=1
tick nếu đúng nha
a: =4+36
=40
b:\(=5\left(3\cdot23-12\right)+4\cdot26\)
\(=5\cdot55+104\)
=275+104
=379
\(a,=4+63=67\\ b,=345+104-60=389\\ c,=151-\dfrac{97}{96}+396=\dfrac{52415}{96}\\ d,=\dfrac{79}{77}-32+575=\dfrac{41890}{77}\\ e,=21+\dfrac{39}{37}+50=\dfrac{2666}{37}\)