a) 7,63 x 12,47 + 12,47 x 2,37 - 2,5 x 40

= 12,47 x (7,63 + 2,37) - 100

= 12,43 x 10 - 100

= 124,3 - 100

= 24,3

b) \(\dfrac{7.5.12}{15.8.4}\) = \(\dfrac{7.5.3.2.2}{3.5.2.2.2.2.2}\) = \(\dfrac{7}{4.2}\)= \(\dfrac{7}{8}\)

(P/s: Dấu "." là dấu x (nhân) đó nha! :>>>)

Chúc bạn học tốt!! ^^

\(a,1,5+2,5+...+8,5=\left(1,5+8,5\right)+\left(2,5+7,5\right)+\left(3,5+6,5\right)+\left(4,5+5,5\right)=10+10+10+10=40\\ b,7,63\times12,47+12,47\times2,37=12,47\times\left(7,63+2,37\right)=12,47\times10=124,7\)

\(c,37,2\times101-37-0,2=37,2\times101-\left(37+0,2\right)=37,2\times101-37,2=37,2\times\left(101-1\right)=37,2\times100=3720\)

\(d,112,37\times4,29-4,29\times12,37=4,29\times\left(112,37-12,37\right)=4,29\times100=429\)

a.

= ( 1,5 + 8,5 ) + ( 2,5 + 7,5 ) + ( 3,5 + 6,5 ) + ( 4,5 + 5,5 )

= 10 + 10 + 10 + 10 

= 40 

b.

= 12,47x(7,63+2,37)

= 12,47x10

=124,7

c.

= 37,2 x 101 - ( 37 + 0,2 )

= 37,2 x 101 - 37,2 x 1

= 37,2 x ( 101 - 1 )

= 37,2 x 100

= 3720

d.

=4,29x(112,37-37)

=4,29x100

=429

a) 17,34 x 99 + 18 - 0,66

= 17,34 x 99 + 17,34 x 1

= 17,34 x (99 + 1)

= 17,34 x 100

= 1734

b) 7,63 x 12,47 + 12,47 x 2,37

= 12,47 x (7,63 + 2,37)

= 12,47 x 10

= 124,7

c) 112,37 x 4,29 - 4,29 x 12,37

= 4,29 x (112,37 - 12,37)

= 4,29 x 100

= 429

d) 17,4 x 52 + 57 x 17,4 - 17,4 x 9

= 17,4 x (52 + 57 - 9)

= 17,4 x 100

= 1740

`9,15:0,5+9,15xx9-9,15`

`=9,15xx2+9,15xx9-9,15xx1`

`= 9,15 xx (2+9-1)`

`= 9,15 xx 10`

`=91,5`

9,15 : 0,5 + 9,15 x 9 - 9,15

\(=9,15:\dfrac{1}{2}+9,15\times9-9,15\times1\)

\(=9,15\times2+9,15\times9-9,15\times1\)

= 9,15 x (2+9-1)

= 9,15 x 10

= 91,5

\(9,15:0,5+9,15\times9-9,15\)

\(=9,15\times\dfrac{10}{5}+9,15\times9-9,15\times1\)

\(=9,15\times2+9,15\times9-9,15\times1\)

\(=9,15\times\left(2+9-1\right)\)

\(=9,15\times10\)

\(=91,5\)

\(BCNN\left(8,6,9\right)=72\\ BCNN\left(9,15\right)=45\\ ƯCLN\left(9,15\right)=3\\ BC\left(8,9,6\right)=B\left(72\right)=\left\{0;72;144;216;...\right\}\\ ƯC\left(9,150\right)=Ư\left(3\right)=\left\{-3;-1;1;3\right\}\)

BCNN(8,6,9)=72

BCNN(9,15)=45

ƯCLN(9,15)=3

BCNN(8,9,6)=0;72;144;216;...

ƯCLN(9,150)=1;3

\(12,49\times12,47=155,7503\)

\(12,48\times12,48=155,7504\)

Vay 12,49.12,47<12,48.12,48

12,47x12,47<12,48x12,48

12,49x12,47 và 12,48x12,48

155.7503    <       155,7504

\(\Rightarrow\)12,49x12,47<12,48x12,48

a) =952,9
b) =116,53
c) =27,051
d) =3,5

a) =952,9 b) =116,53 c) =27,051 d) =3,5

a) =952,9
b) =116,53
c) =27,051
d) =3,5