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a: =15+11,2=26,2
b: =-3
c: =-1,9-0,02=-1,92
d: =103-96-0,08=7-0,08=6,92
e: =15-0,99=14,01
f: -0,707+2,3=1,593
p: =8,26-25,14-8,26=-25,14
q: =-5,4(3,6+6,4)
=-5,4*10=-54
o: =12,7+(-7)
=5,7
m: =19,7-9=10,7
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0,48x700-2,4x45x2
=0,48x(700-5x45x2)
=0,48x(700-450)
=0,48x250
=120
4,5+3,5+2,5+1,5+0,5-4-3-2-1
=(4,5-4)+(3,5-3)+(2,5-2)+(1,5-1)+0,5
=0,5+0,5+0,5+0,5+0,5
=0,5x5
=2,5
![](https://rs.olm.vn/images/avt/0.png?1311)
Giải:
a) \(\left(9\dfrac{4}{9}+5\dfrac{2}{3}\right)-5\dfrac{1}{2}\)
\(=\left(\dfrac{85}{9}+\dfrac{17}{3}\right)-\dfrac{11}{2}\)
\(=\dfrac{136}{9}-\dfrac{11}{2}\)
\(=\dfrac{173}{18}\)
b) \(\dfrac{13}{9}.\dfrac{15}{4}-\dfrac{13}{9}.\dfrac{7}{4}-\dfrac{13}{9}.\dfrac{5}{4}\)
\(=\dfrac{13}{9}.\left(\dfrac{15}{4}-\dfrac{7}{4}-\dfrac{5}{4}\right)\)
\(=\dfrac{13}{9}.\dfrac{3}{4}\)
\(=\dfrac{13}{12}\)
c) \(\dfrac{2}{3}+\dfrac{5}{8}-\dfrac{-1}{3}+0,375\)
\(=\left(\dfrac{2}{3}-\dfrac{-1}{3}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)
\(=1+1\)
\(=2\)
d) \(75\%-3\dfrac{1}{2}+1,5:\dfrac{10}{7}\)
\(=\dfrac{3}{4}+\dfrac{7}{2}+\dfrac{3}{2}:\dfrac{10}{7}\)
\(=\dfrac{3}{4}+\dfrac{7}{2}+\dfrac{21}{20}\)
\(=\dfrac{53}{10}\)
e) \(1\dfrac{13}{15}.\left(0,5\right)^2.3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right):1\dfrac{23}{24}\)
\(=\dfrac{28}{15}.\dfrac{1}{4}.3+\left(\dfrac{8}{15}-\dfrac{79}{60}\right):\dfrac{47}{24}\)
\(=\dfrac{7}{5}+\dfrac{-47}{60}:\dfrac{47}{24}\)
\(=\dfrac{7}{5}+\dfrac{-2}{5}\)
\(=1\)
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Bài 3:
Tổng số tiền đã tiêu là;
\(2.5\cdot27500+5.4\cdot52000+2\cdot12500=374550\left(đồng\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a) \(\dfrac{5}{2}+\left(\dfrac{-3}{2}\right)^2\cdot6-\left|-5\right|\)
\(=\dfrac{5}{2}+\dfrac{9}{4}\cdot6-5\)
\(=2,5+13,5-5\)
\(=11\)
b) \(\dfrac{250^3}{50^3}=\dfrac{50^3\cdot5^3}{50^3}=5^3=125\)
Bài 2:
\(A=\left|x+1,5\right|-4,5\)
Vì \(\left|x+1,5\right|\ge0\forall x\)
\(\Rightarrow\left|x+1,5\right|-4,5\ge-4,5\ge0\forall x\)
Dấu "=" xảy ra \(\Leftrightarrow x+1,5=0\Rightarrow x=-1,5\)
Vậy MIN \(A=-4,5\Leftrightarrow x=-1,5\)
Bài 1 :
a. \(\dfrac{5}{2}+\left(\dfrac{-3}{2}\right)^2.6-\left|-5\right|\)
\(=\dfrac{5}{2}+\dfrac{9}{4}.6-5\)
\(=\dfrac{5}{2}+\dfrac{27}{2}-5\)
\(=11\)
b. \(\dfrac{250^3}{50^3}=\left(\dfrac{250}{50}\right)^3=5^3=125\)
c. \(\dfrac{45^{10}.5^{20}}{75^{15}}=\dfrac{\left(5.3.3\right)^{10}.5^{20}}{\left(5.5.3\right)^{15}}=\dfrac{5^{10}.3^{10}.3^{10}.5^{20}}{5^{15}.5^{15}.3^{15}}=\dfrac{5^{30}.3^{20}}{5^{30}.3^{15}}=3^5=243\)
Bài 2 :
\(A=\left|x-1,5\right|-4,5\)
Vì \(\left|x-1,5\right|\ge0\) \(\forall x\)
\(\Rightarrow\left|x-1,5\right|-4,5\ge0-4,5=-4,5\)
hay Amin \(\ge-4,5\)
Amin = -4,5 khi :
\(\left|x-1,5\right|=0\)
\(\Rightarrow x+1,5=0\)
\(\Rightarrow x=-1,5\)
Vậy Amin = -4,5 khi \(x=-1,5\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(17.8+51.4=34.4+51.4=4\left(51+34\right)=4.84=336\) \(2.2.3.5.19=\left(2.5\right).\left(3.19\right).2=10.2.57=570.2=1140\) \(54.275+825.15+275=54.275+45.275+275=275\left(54+45+1\right)=100.275=27500\) \(\frac{167.198+98}{198.168-100}=\frac{167.198+98}{198.167+198-100}=\frac{167.198+98}{167.198+98}=1\)
\(\frac{1}{n}-\frac{1}{n+k}=\frac{k}{n\left(n+k\right)}\Rightarrow\frac{1}{1.2}+\frac{1}{2.3}+.....+\frac{1}{2019.2020}=1-\frac{1}{2}+\frac{1}{2}-....-\frac{1}{2020}=1-\frac{1}{2020}=\frac{2019}{2020}\)
a) 17 x 8 + 51 x 4
= 17 x 4 x 2 + 17 x 3 x 4
= 17 x 4 x ( 2 + 3 )
= 14 x 4 x 5
= 14 x 20
= 280
b) 2 x 2 x 3 x 5 x 19
= ( 2 x 5 ) x ( 3 x 19 ) x 2
= 10 x 57 x 2
= 570 x 2
= 1140
c) 54 x 275 + 825 x 15 + 275
= 54 x 275 + 275 x 3 x 15 + 275 x 1
= 54 x 275 + 275 x 45 + 275 x 1
= 275 x ( 54 + 45 + 1 )
= 275 x 100
= 27500
d) 100 - 99 + 98 - 97 + 96 - 95 + 94 - 93 + ... + 4 - 3 + 2
= (100 - 99) + (98 - 97) + (96 - 95) + (94 - 93) + ... + (4 - 3) + 2
= (1 + 1 + ... + 1) + 2
( 49 số 1 )
= 49 + 2
= 51
k) 1,5 + 2,5 + 3,5 + 4,5 + 5,5 + 6,5 + 7,5 + 8,5
= ( 1,5 + 8,5 ) + ( 2,5 + 7,5 ) + ( 3,5 + 6,5 ) + ( 4,5 + 5,5 )
= 10 + 10 + 10 + 10
= 40
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a)25,52 - x : 2,5 = 4,61
x : 2,5 = 25,52 - 4,61
x ; 2,5 = 20,91
x = 20,91 x 2,5
x = 52,275
b) 12,6 - x + 4,5 = 4,61
12,6 - x = 4,61 - 4,5
12,6 - x = 0,11
x = 12,6 - 0,11
x = 12,49
c) x - 75/100 = 125/100 + 9/10
x - 0,75 = 1,25 + 0,9
x - 0,75 = 2,15
x = 2,15 + 0,75
x = 2,90
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Bạn có thể viết rõ hơn ra được không ạ . Chứ mình nhìn nó ra nhiều trường hợp lắm .
\(\frac{3}{4}.4,5+\frac{15}{10}.3,5-\frac{75}{100}.1,5\)
\(=0,75+4,5+0,5+3,5+0,75+1,5\)
\(=0,75+\left(4,5+3,5+1,5\right)+0,5\)
\(=0,75+10+0,5\)
\(=10,75+0,5\)
\(=11,25\)