a)17.25=25.17=25.(1+16)=25.1+25.16=25+25.4.4=25+100.4=25+400=425

b)281+129+219=281+219+129=500+129=629

c)2³.2²+5⁵:5³=2³⁺²+5^5-3=2⁵+5²=32+25=57

d)29.31+66.69+31.37=31.(29+37)+66.69=31.66+66.69=66.(31+69)=66.100=6600

a. 17.25 = 425

b. 281+129+219 = (281 + 219) + 129 = 500 + 129 = 629

c. 2³.2²+5⁵:5³ = 2⁵+5²=32+25=57

d. 29.31+66.69+31.37

= 29.31+31.37+66.69

= 31.(29+37)+66.69

= 31.66+66.69

= 66.(31 + 69)

= 66.100

= 6600

a)17.25=425

b)281+129+219=(281+219)+129=1000+129=1129

c)2^3.2^2+5^5:5^3=2^(3+2) +5^(5-3)=2^5+5^2=32+25=57

d)29.31+66.69+31.37=31(29+37)+66.69=31.66+66.69=66(31+69)=66.100=3100

nhìn thì dể làm được nhưng biếng làm

hihi

nhìu quá mk hoa mắt mất *_*

mk làm câu 1 thui nhé hihi!

29.31+66.69+31.37

=31.(29+37)+66.69

=31.66+66.69

=66.(31+69)

=66.100=6600

1,35326087

-2/3

0

-6/29/44

-9

nha bạn

Bài 1: 

Ta có: \(x-35\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow65\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow x=\dfrac{1}{25}:\dfrac{13}{20}=\dfrac{1}{25}\cdot\dfrac{20}{13}=\dfrac{4}{65}\)

Vậy: \(x=\dfrac{4}{65}\)

Bài 2: 

a) Ta có: \(17\dfrac{2}{31}-\left(\dfrac{15}{17}+6\dfrac{2}{31}\right)\)

\(=17\dfrac{2}{31}-\dfrac{15}{17}-6\dfrac{2}{31}\)

\(=11+\dfrac{2}{31}-\dfrac{15}{17}\)

\(=\dfrac{5366}{527}\)

4: \(=\dfrac{2+3}{7}+\dfrac{1+6}{9}-\dfrac{5}{6}=\dfrac{5}{7}+\dfrac{7}{9}-\dfrac{5}{6}=\dfrac{83}{126}\)

5: \(=\dfrac{-5-2}{7}+\dfrac{3+1}{4}-\dfrac{1}{5}=-\dfrac{1}{5}\)

6: \(=\dfrac{-3-28}{31}+\dfrac{-6-1}{17}+\dfrac{1-5}{25}=-1-\dfrac{7}{17}-\dfrac{4}{25}=-\dfrac{668}{425}\)

4. \(\dfrac{2}{7}+\dfrac{1}{9}+\dfrac{3}{7}+\dfrac{5}{9}+\dfrac{-5}{6}\)

\(=\left(\dfrac{2}{7}+\dfrac{3}{7}\right)+\left(\dfrac{1}{9}+\dfrac{5}{9}\right)+\dfrac{-5}{6}\)

\(=\dfrac{5}{7}+\dfrac{2}{3}+\dfrac{-5}{6}\)

\(=\dfrac{30+28+\left(-35\right)}{42}=\dfrac{23}{42}\)
 

5. \(\dfrac{-5}{7}+\dfrac{3}{4}+\dfrac{-1}{5}+\dfrac{-2}{7}+\dfrac{1}{4}\)

\(=\left(\dfrac{-5}{7}+\dfrac{-2}{7}\right)+\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\dfrac{-1}{5}\)

\(=\dfrac{-7}{7}+\dfrac{4}{4}+\dfrac{-1}{5}\)

\(=-1+1+\dfrac{-1}{5}\)

\(=-\dfrac{1}{5}\)
 

6. \(\dfrac{-3}{31}+\dfrac{-6}{17}+\dfrac{1}{25}+\dfrac{-28}{31}+\dfrac{-1}{17}+\dfrac{-1}{5}\)

\(=\left(\dfrac{-3}{31}+\dfrac{-28}{31}\right)+\left(\dfrac{-6}{17}+\dfrac{-1}{17}\right)+\dfrac{1}{25}+\dfrac{-1}{5}\)

\(=\dfrac{-31}{31}+\dfrac{-7}{17}+\dfrac{1}{25}+\dfrac{-1}{5}\)

\(=-1+\dfrac{-7}{17}+\dfrac{1}{25}+\dfrac{-1}{5}\)

\(=\dfrac{-425+\left(-175\right)+17+\left(-85\right)}{425}=\dfrac{-668}{425}\)

a=897

b=8668

c=7

d=3671

a,=29.(69+31)-2300

=29.100-2300

=2900-2300

=600

MK NÓI THẬT MẤY BÀI NÀY DỄ ỢT

a) 29 x( 69+31) -2300

=29X 100 -2300

=2900-2300

=600

c) 3^11:3^9 - 98: 7^2

=3^(11-9) - 98:49

=3^2-2

=9-2=7

d) 2011+5( 300-(17-7^2))

=2016 (300-(17-49)

=2016 (300-(-32)

= 2016 332

=134531712

\(a)\)

\(\left(-31\right)+\left(50-19\right)-\left(150-31\right)\)

\(=\left(-31\right)+50-19-150+31\)

\(=\left(-150\right)-19\)

\(=-169\)

\(b)\)

\(25.\left(45-17\right)-45.\left(25-17\right)\)

\(=25.45-25.17-45.25+45.17\)

\(=0\)

\(c)\)

\(\frac{-1}{12}+\frac{4}{3}=\frac{5}{4}\)

\(d)\)

\(3+\frac{-5}{20}+\frac{30}{75}+\frac{-7}{4}\)

\(=\left(\frac{3}{5}+\frac{30}{75}\right)-\left(\frac{5}{20}+\frac{7}{4}\right)\)

\(=1-2\)

\(=-1\)

a) (-31)+(50-19)-(150-31)

= (-31)+50+(-19)-150+(-31)
= (-31)+50-150+(-19)-(-31)
= (-31)+(-100)+12
= -119
b) 25(45-17)-45(25-17)
= 25.45-25.17-45.25-45.17
= 25(45-45)-25(17-17)
= 0
c) -1/12 + 4/3
= -1/12 + 16/12
= 15/12
= 5/4
d) 3/5+(-5)/20+30/75+(-7)/4
= 45/75+30/75+(-5)/20+(-35)/20
= 1+(-2)
= -1