a)11/4 + ( -3/5 + 1/3) : -4/9
b) 2/6 - (-3/3 + 4/7) : -9/5
c) 21 - 15/4 : ( 3/8 -1/6)
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`4/7+4`
`=4/7+4/1`
`=4/7+28/7`
`=32/7`
__
`3+6/11`
`=33/11+6/11`
`=39/11`
__
`3-5/7`
`=3/1-5/7`
`=21/7-5/7`
`=16/7`
__
`21/9-2`
`=21/9-18/9`
`=3/9`
`=1/3`
__
`15/24+2`
`=15/24+48/24`
`=63/24`
`=21/16`
__
`63/45-20/25`
`=63/45-4/5`
`=63/45-36/45`
`=27/45`
`=9/15`
__
`3/4-2/8`
`=3/4-1/4`
`=2/4`
__
`6/7-5/8`
`=48/56-35/56`
`=13/56`
__
`37/45-5/9`
`=37/45-25/45`
`=12/45`
`=4/15`
__
`46/39-11/13`
`=46/39-33/39`
`=13/39`
`=1/2`
__
`5/12+3/4+1/3`
`=5/12+9/12+4/12`
`=14/12+4/12`
`=18/12`
`=3/2`
__
`1/2+3/7+11/14`
`=7/14+6/14+11/14`
`=13/14+11/14`
`=24/14`
`=12/7`
__
`7/10-(1/5+1/4)`
`=7/10-(4/20+5/20)`
`=7/10-9/20`
`=14/20-9/20`
`=5/20`
`=1/4`
__
`15/4-2/3-3/4`
`=(15/4-3/4)-2/3`
`=12/4-2/3`
`=3-2/3`
`=9/3-2/3`
`=7/3`
lệnh for...to...do:
a)program tinh_tong;
uses crt;
var i,s:byte;
begin
clrscr;
s:=0;
for i:=1 to 9 do s:=s+i;
write(s);
readln;
end.
b)
program tinh_tong;
uses crt;
var i,s:byte;
begin
clrscr;
s:=0;
for i:=1 to 14 do
begin
if i mod 2=0 then
s:=s+i;
end;
write(s);
readln;
end.
c)
program tinh_tong;
uses crt;
var i,s:byte;
begin
clrscr;
s:=0;
for i:=1 to 15 do
begin
if i mod 2=1 then
s:=s+i;
end;
write(s);
readln;
end.
lệnh while...do
a)program tinh_tong;
uses crt;
var i,s:byte;
begin
clrscr;
s:=0;
i:=1;
while i<=9 do
begin
s:=s+i;
i:=i+1;
end;
write(s);
readln;
end.
b)program tinh_tong;
uses crt;
var i,s:byte;
begin
clrscr;
s:=0;
i:=1;
while i<=14 do
begin
if i mod 2=0 then
s:=s+i
else i:=i+1;
end;
write(s);
readln;
end.
c)
program tinh_tong;
uses crt;
var i,s:byte;
begin
clrscr;
s:=0;
i:=1;
while i<=15 do
begin
if i mod 2=1 then
s:=s+i
else i:=i+1;
end;
write(s);
readln;
end.
Bài 1: Tính
\(\text{1)}\) \(\dfrac{5}{8}.\dfrac{7}{30}-\dfrac{5}{2}.\dfrac{1}{8}\)
\(=\dfrac{5}{8}.\dfrac{7}{30}-\dfrac{5}{8}.\dfrac{1}{2}\)
\(=\dfrac{5}{8}.\left(\dfrac{7}{30}-\dfrac{1}{2}\right)\)
\(=\dfrac{5}{8}.\dfrac{-4}{15}\)
\(=\dfrac{-1}{6}\)
\(\text{2)}\) \(\dfrac{21}{10}.\dfrac{3}{4}-\dfrac{21}{10}-\dfrac{3}{4}\)
\(=\dfrac{63}{40}-\dfrac{21}{10}-\dfrac{3}{4}\)
\(=\dfrac{-21}{40}-\dfrac{3}{4}\)
\(=\dfrac{-51}{40}\)
\(\text{3)}\) \(\dfrac{-4}{11}:\dfrac{-6}{11}\)
\(=\dfrac{-4}{11}.\dfrac{11}{-6}\)
\(=\dfrac{4}{6}\)
\(\text{4)}\) \(\dfrac{2}{7}.\dfrac{14}{3}-1\)
\(=\dfrac{4}{3}-1\)
\(=\dfrac{1}{3}\)
\(\text{5)}\) \(\dfrac{4}{7}:\left(\dfrac{1}{5}.\dfrac{4}{7}\right)\)
\(=\dfrac{4}{7}:\dfrac{1}{5}:\dfrac{4}{7}\)
\(=1:\dfrac{1}{5}\)
\(=5\)
\(\text{6)}\) \(\dfrac{12}{7}.\dfrac{7}{4}+\dfrac{35}{11}:\dfrac{245}{121}\)
\(=3+\dfrac{35}{11}.\dfrac{121}{245}\)
\(=3+\dfrac{11}{7}\)
\(=3\dfrac{11}{7}=\dfrac{32}{7}\)
\(\text{7)}\) \(\left(\dfrac{4}{3}+\dfrac{8}{3}\right).\left(\dfrac{7}{4}-\dfrac{6}{4}\right):\left(\dfrac{6}{5}+\dfrac{12}{5}+\dfrac{1}{5}\right)\)
\(=4.\left(\dfrac{7}{4}-\dfrac{6}{4}\right):\left(\dfrac{6}{5}+\dfrac{12}{5}+\dfrac{1}{5}\right)\)
\(=4.\dfrac{1}{4}:\left(\dfrac{6}{5}+\dfrac{12}{5}+\dfrac{1}{5}\right)\)
\(=4.\dfrac{1}{4}:\dfrac{19}{5}\)
\(=1:\dfrac{19}{5}\)
\(=\dfrac{5}{19}\)
\(\text{8)}\) \(\left(\dfrac{1}{4}-\dfrac{1}{4}+\dfrac{\dfrac{1}{9}}{\dfrac{1}{9}}\right):\left(\dfrac{2}{3}+\dfrac{\dfrac{7}{15}}{\dfrac{2}{5}}-\dfrac{1}{6}\right)\)
\(=\left(0+1\right):\left(\dfrac{2}{3}+\dfrac{7}{15}:\dfrac{2}{5}-\dfrac{1}{6}\right)\)
\(=1:\left(\dfrac{2}{3}+\dfrac{7}{6}-\dfrac{1}{6}\right)\)
\(=1:\left(\dfrac{2}{3}+1\right)\)
\(=1:\dfrac{5}{3}\)
\(=\dfrac{3}{5}\)
\(\text{9)}\)
\(\left[\left(\dfrac{2}{193}-\dfrac{3}{389}\right).\dfrac{193}{17}+\dfrac{33}{34}\right]:\left[\left(\dfrac{7}{1931}-\dfrac{11}{3862}\right).\dfrac{1931}{25}+\dfrac{9}{2}\right]\)
\(=\left[\dfrac{199}{75077}.\dfrac{193}{17}+\dfrac{33}{34}\right]:\left[\left(\dfrac{7}{1931}-\dfrac{11}{3862}\right).\dfrac{1931}{25}+\dfrac{9}{2}\right]\)
\(=\left[\dfrac{199}{6613}+\dfrac{33}{34}\right]:\left[\left(\dfrac{7}{1931}-\dfrac{11}{3862}\right).\dfrac{1931}{25}+\dfrac{9}{2}\right]\)
\(=\dfrac{13235}{13226}:\left[\left(\dfrac{7}{1931}-\dfrac{11}{3862}\right).\dfrac{1931}{25}+\dfrac{9}{2}\right]\)
\(=\dfrac{13235}{13226}:\left[\dfrac{3}{3862}.\dfrac{1931}{25}+\dfrac{9}{2}\right]\)
\(=\dfrac{13235}{13226}:\left[\dfrac{3}{50}+\dfrac{9}{2}\right]\)
\(=\dfrac{13235}{13226}:\dfrac{114}{25}\)
\(=\dfrac{330875}{1507764}\)
1) \(\frac{5}{8}.\frac{7}{3}-\frac{5}{2}.\frac{1}{8}=\frac{5}{8}.\frac{7}{3}-\frac{5}{8}.\frac{1}{2}=\frac{5}{8}\left(\frac{7}{3}-\frac{1}{2}\right)=\frac{5}{8}.\frac{11}{6}=\frac{55}{48}\)
2) \(\frac{21}{10}.\frac{3}{4}-\frac{21}{10}.\frac{3}{4}=\frac{21}{10}\left(\frac{3}{4}-\frac{3}{4}\right)=\frac{21}{10}.0=0\)
3) \(\frac{-4}{11}:\frac{-6}{11}=\frac{-4}{11}.\frac{-11}{6}=\frac{-4.\left(-11\right)}{11.6}=\frac{-4.\left(-1\right)}{1.6}=\frac{4}{6}=\frac{2}{3}\)
4)\(\frac{2}{7}.\frac{14}{3}-1=\frac{2.14}{7.3}-1=\frac{2.2}{1.3}-1=\frac{4}{3}-1=\frac{1}{3}\)
5)\(\frac{4}{7}:\left(\frac{1}{5}.\frac{4}{7}\right)=\frac{4}{7}:\frac{4}{35}=\frac{4}{7}.\frac{35}{4}=\frac{4.35}{7.4}=\frac{1.5}{1.1}=5\)
6) \(\frac{12}{7}.\frac{7}{4}+\frac{35}{11}:\frac{245}{121}=\frac{12.7}{7.4}+\frac{35}{11}.\frac{121}{245}=\frac{3.1}{1.1}+\frac{35}{11}.\frac{121}{245}=3+\frac{35}{11}.\frac{121}{245}=3+\frac{35.121}{11.245}=\frac{1.11}{1.7}=\frac{11}{7}\)
Giải:
A=5/9+2/15-6/9
=(5/9-6/9)+2/15
= -1/9 + 2/15
= 1/45
B=2/7-3/8+4/7+1/7-5/8+5/15
= (2/7+4/7+1/7) + (-3/8-5/8) +1/3
= 1+ (-1) +1/3
=1/3
C=3/5+1/15+1/57+1/3-2/9-3/4-1/36
=9/15+1/15+1/57+19/57-8/36-27/36-1/36
=(9/15+1/15)+(1/57+19/57)+(-8/36-27/36-1/36)
=2/3+20/57+(-1)
=58/57+(-1)
=1/57
D=1/1.2+1/2.3+1/3.4+...+1/99.100
=1/1-1/2+1/2-1/3+1/3-1/4+...+1/99-1/100
=1/1-1/100
=99/100
Câu E mình ko biết làm nhé!
a: \(\dfrac{11}{4}+\left(-\dfrac{3}{5}+\dfrac{1}{3}\right):\dfrac{-4}{9}\)
\(=\dfrac{11}{4}+\dfrac{-9+5}{15}\cdot\dfrac{9}{-4}\)
\(=\dfrac{11}{4}+\dfrac{-4}{15}\cdot\dfrac{9}{-4}\)
\(=\dfrac{11}{4}+\dfrac{3}{5}=\dfrac{55+12}{20}=\dfrac{67}{20}\)
b: \(\dfrac{2}{6}-\left(-\dfrac{3}{3}+\dfrac{4}{7}\right):\dfrac{-9}{5}\)
\(=\dfrac{2}{6}-\left(-1+\dfrac{4}{7}\right)\cdot\dfrac{-5}{9}\)
\(=\dfrac{2}{6}-\dfrac{-3}{7}\cdot\dfrac{-5}{9}\)
\(=\dfrac{1}{3}-\dfrac{15}{63}\)
\(=\dfrac{6}{63}=\dfrac{2}{21}\)
c: \(21-\dfrac{15}{4}:\left(\dfrac{3}{8}-\dfrac{1}{6}\right)\)
\(=21-\dfrac{15}{4}:\dfrac{3\cdot3-4}{24}\)
\(=21-\dfrac{15}{4}\cdot\dfrac{24}{5}\)
\(=21-3\cdot6=3\)
\(a.\dfrac{11}{4}+\left(-\dfrac{3}{5}+\dfrac{1}{3}\right):-\dfrac{4}{9}\)
\(=\dfrac{11}{4}+\left(-\dfrac{4}{15}\right):-\dfrac{4}{9}\)
\(=\dfrac{11}{4}+\dfrac{3}{5}=\dfrac{67}{20}\)
\(b.\dfrac{2}{6}-\left(-\dfrac{3}{3}+\dfrac{4}{7}\right):-\dfrac{9}{5}\)
\(=\dfrac{2}{6}-\left(-\dfrac{3}{7}\right):-\dfrac{9}{5}\)
\(=\dfrac{2}{6}-\dfrac{5}{21}=\dfrac{2}{21}\)
\(c.21-\dfrac{15}{4}:\left(\dfrac{3}{8}-\dfrac{1}{6}\right)\)
\(=21-\dfrac{15}{4}:\dfrac{5}{24}\)
\(=21-18=3\)