3 3/4 + 1 1/2 - 2 1/4
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Tuổi con chiếm 1 phần thì tuổi mẹ chiếm 5 phần
Khi tuổi mẹ gấp 8 lần tuổi con thì:
Tuổi con là :
28 : (5 - 1) = 7(tuổi)
Tuổi mẹ là:
7 x 5 = 35(tuổi)
`1/2 xx 1/3 xx 1/4`
`= (1xx1xx1)/(2xx3xx4)`
`= 1/24`
__
`1/2 xx 1/3 : 1/4`
`= 1/2 xx 1/3 xx 4`
`= (1xx1xx4)/(2xx3)`
`= 4/6`
`=2/3`
__
`1/2 : 1/3 xx1/4`
`= 1/2 xx 3 xx 1/4`
`=(1xx3xx1)/(2xx4)`
`= 3/8`
__
`1/2 : 1/3 : 1/4`
`= 1/2 xx 3xx4`
`= 12/2`
`=6`
`1/2xx1/3xx1/4`
`=1/24`
`1/2xx1/3:1/4`
`=1/6xx4`
`=4/6=2/3`
`1/2:1/3xx1/4`
`=1/2xx3xx1/4`
`=3/2xx1/4`
`=3/8`
`1/2:1/3:1/4`
`=1/2xx3xx4`
`=6`
1)\(25x+3\left(4-6x\right)=50\)
\(25x+12-18x=50\)
\(7x+12=50\)
\(7x=38\)
\(x=\frac{38}{7}\)
2)\(4\left(2x+3\right)+2\left(3x+1\right)=120\)
\(8x+12+6x+2=120\)
\(14x+14=120\)
\(14x=106\)
\(x=\frac{53}{7}\)
`@` `\text {Ans}`
`\downarrow`
\(\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times\left(1-\dfrac{1}{5}\right)...\left(1-\dfrac{1}{1000}\right)\)
`=`\(\left(\dfrac{2}{2}-\dfrac{1}{2}\right)\times\left(\dfrac{3}{3}-\dfrac{1}{3}\right)\times\left(\dfrac{4}{4}-\dfrac{1}{4}\right)...\left(\dfrac{1000}{1000}-\dfrac{1}{1000}\right)\)
`=`\(\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times...\times\dfrac{999}{1000}\)
`=`\(\dfrac{1}{1000}\)
\(=\dfrac{1}{2}.\dfrac{2}{3}.\dfrac{3}{4}.\dfrac{4}{5}.......\dfrac{99}{100}=\dfrac{1}{100}\)
3/2.(x-5/3)+4/5=x+1
3/2.x-3/2.5/3+4/5=x+1
3/2.x-5/2-x=1+4/5
3/2.x-5/2-x=9/5
3/2.x-x=9/5+5/2
1/2.x=43/10
x=43/10:1/2
x=43/5
1+(-2)+3+(-4)+...+2001+(-2002)+2003
=[1+(-2)]+[3+(-4)]+...+[2001+(-2002)]+2003 (có tất cả 1001 cặp)
=(-1)+(-1)+...+(-1)+2003
=(-1).1001+2003
=(-1001)+2003
=1002
Học tốt!
#Huyền#
1 +( -2) + 3 + (-4) +...+2001 + (-2002) + 2003
= [1 +( -2)] + [3 + (-4)] +...+ [-2000+2001] + [(-2002) + 2003]
= -1 + -1 +............ + 1 + 1= 0
a, 2x3x4x8x25x125= (2x3)x(4x25)x(8x125)= 6x100x1000=600000
b,42/5 +56/9+23/4+3/5+1/3+1/4= (42/5+3/5)+(23/4+1/4)+(56/9+1/3)=9+6+59/9=
7/3 - 2/3 . x = 7/4
2/3 . x = 7/3 - 7/4
2/3 . x = 28/12 - 21/ 12
2/3 . x = 7/12
x = 7/12 : 2/3
x = 7/12 . 3/2
x = 21/ 24
x = 7/8
vậy x = 7/8
\(\frac{7}{3}-\frac{2}{3}x=-1\frac{3}{4}\)
\(\frac{7}{3}-\frac{2}{3}x=-\frac{7}{4}\)
\(\frac{2}{3}x=\frac{7}{3}-\left(-\frac{7}{4}\right)\)
\(\frac{2}{3}x=\frac{7}{3}+\frac{7}{4}\)
\(\frac{2}{3}x=\frac{49}{12}\)
\(x=\frac{49}{12}:\frac{2}{3}\)
\(x=\frac{49}{12}\cdot\frac{3}{2}\)
\(x=\frac{49}{8}\)
nếu thấy đúng thì k cho mh nhahoàng mộc miên123___
\(3\frac{3}{4}+1\frac{1}{2}-2\frac{1}{4}=\frac{15}{4}+\frac{3}{2}-\frac{9}{4}\)
\(=\frac{21}{4}-\frac{9}{4}=3\)
ti ck nha
\(3\frac{3}{4}+1\frac{1}{2}-2\frac{1}{4}\)
\(=\left(3\frac{3}{4}-2\frac{1}{4}\right)+1\frac{1}{2}\)
\(=1\frac{2}{4}+1\frac{1}{2}\)
\(=\frac{3}{2}+\frac{3}{2}\)
\(=\frac{6}{2}=3\)