vì A có 100 thừa số nên thừa số thứ 100 là 100-n=100-100=0

A=(100 - 1) . (100 - 2) . (100 - 3) ...(100 - n) =(100 - 1) . (100 - 2) . (100 - 3) ...0=0

b, B=13a + 19b + 4a – 2b=17a+17b=17.(a+b)=17.100=1700

a) x-2014=2013

-> x= 2013+2014

->x=4027

b) x:18=25

-> x= 25.18

-> x= 450

c) (1+3+5+...+101).x=0

->1+3+5+...+101 hoặc x phải bằng 0 mà 1+3+5+...+101 không thể bằng 0 

->x=0

d) x.( 2013+2014+2015 ) = 0

-> x hoặc ( 2013+2014+2015 ) một trong hai cái phải bằng 0 nhưng 2013+2014+2015 không thể bằng 0 

->x=0

e) x.125=10000

-> x=10000:125

->x=80

f) 679 : [(15.x + 364):x] =17

->[(15x+364):x] = 697:17 = 41

->(15x + 364):x = 41

->15x + 364 = 41x

->364 = 41x - 15x = 26x

-> 364 = 26x

-> x = 364 : 26

-> x=14

    hok tốt:)

a, x-2014=2013

    x         =2013+2014

    x         =4027

b, x:18=25

     x     =25.18

     x=450

c, (1+3+5+...+101).x=0

x=0:(1+3+5+...+101)

x=0

d, tương tự phần c

e, x.125=10000

x=10000:125

x=80

f, 697:[(15x+364):x]=17

15+364:x=697:17

364x=41-15=26

x=26:364=\(\frac{1}{4}\)

Đáp án:

 a, 38+41+117+159+6238+41+117+159+62

=(38+62)+(41+159)+117=(38+62)+(41+159)+117

=100     +200      +117=100     +200      +117

=417=417

b, 73+86+968+914+303273+86+968+914+3032

=73+(86+914)+(968+3032)=73+(86+914)+(968+3032)

=73+1000     +4000=73+1000     +4000

=5073=5073

c, 341.67+341.16+659.83341.67+341.16+659.83

=341.(67+16)+659.83=341.(67+16)+659.83

=341.83+659.83=341.83+659.83

=83.(341+659)=83.(341+659)

=83.1000=83000=83.1000=83000

d, 42.53+47.156−47.11442.53+47.156-47.114

=42.53+47.(156−114)=42.53+47.(156-114)

=42.53 +47.42=42.53 +47.42

=42.(53+47)=42.100=42.(53+47)=42.100

=4200=4200

e, 563.23+23.26+23563.23+23.26+23

=23.(563+26+1)=23.(563+26+1)

=23.600=23.600

=13800=13800

f, 132+157+43+68132+157+43+68

=(132+68)+(157+43)=(132+68)+(157+43)

=200      +200=400=200      +200=400

g, 49.68+100.34+6849.68+100.34+68

=49.68+50.68+68=49.68+50.68+68

=68.(49+50+1)=68.(49+50+1)

=68.100=6800=68.100=6800

h, 491.(267+53)+491.(151+67)491.(267+53)+491.(151+67)

=491.(267+53+151+67)=491.(267+53+151+67)

=491.538=491.538

=264158=264158

Vote mk nha.

29121,36725 là kq nhé hok tốt

\(A=-2.\left(1-\frac{1}{6}+\frac{1}{8}\right)+\frac{5}{12}.\left(\frac{-7}{6}+\frac{1}{4}\right):\frac{-5}{12}\)

\(A=-2.\left(\frac{24-4+3}{24}\right)+\frac{5}{12}.\left(\frac{-28+6}{24}\right).\frac{-12}{5}\)

\(A=-2.\frac{23}{24}+\frac{5}{12}.\frac{-22}{24}.\frac{-12}{5}\)

\(A=\frac{-23}{12}+\frac{-11}{12}\)

\(A=-\frac{17}{6}\)