a, $-28\cdot41+100\cdot141+41\cdot(-72)$

$=41\cdot[(-28)+(-72)]+100\cdot141$

$=41\cdot(-100)+(-100)\cdot(-141)$

$=(-100)\cdot[41+(-141)]$

$=(-100)\cdot(-100)$

$=100\cdot100$

$=10000$

b, $35\cdot(65-6)-65\cdot(35+6)$

$=35\cdot65+35\cdot(-6)-65\cdot35-65\cdot6$

$=(35\cdot65-65\cdot35)+[35\cdot(-6)+65\cdot(-6)]$

$=0+(-6)\cdot(35+65)$

$=-6\cdot100$

$=-600$

c, $-48+48\cdot(-78)-21\cdot48$

$=-48\cdot1+(-48)\cdot78+(-48)\cdot21$

$=-48\cdot(1+78+21)$

$=-48\cdot(79+21)$

$=-48\cdot100$

$=-4800$

`48/84=(48:2)/(84:2)=24/42=(24:2)/(42:2)=12/21=(12:3)/(21:3)=4/7`

\(\dfrac{48}{84}=\dfrac{24}{42}=\dfrac{12}{21}=\dfrac{4}{7}\)

4/7

B

B

b,b

b, b

a/ 25 x ( 32 + 47 ) - 32 x ( 25 + 47 )

= 25 x 79 - 32 x 72

= 1975 - 2304

= -329

b/ 48 x ( 21- 19 ) - 21 x ( 48 - 19 ) + 27 x ( -81 )

= 48 x 2 - 21 x 29 + 27 x ( -81 )

= 96 - 609 + -2187

= -2700

cau co phai vu phuong huyen ko.Neu phai thi cau hay vao ket ban voi to

a) 25.(32+47)-32.(25+47)

=25.32+25.47-32.25+32.47

=32.(25-25-47)+25.47

=32.(-47)+25.47

=47.((-32)+25)

=47.(-7)

=-329.

b) làm tương tự phần a bạn nha.

a: \(65\cdot48+35\cdot48+12\cdot58-12\cdot38\)

\(=48\left(65+35\right)+12\left(58-38\right)\)

\(=48\cdot100+12\cdot20\)

\(=4800+240=5040\)

b: \(2018^2+\left\{15^2:\left[175-\left(2^3\cdot5^2-6\cdot25\right)\right]\right\}\)

\(=1+\left\{\dfrac{225}{175-\left(8\cdot25-150\right)}\right\}\)

\(=1+\dfrac{225}{175-\left(200-150\right)}\)

\(=1+\dfrac{225}{175-50}=1+\dfrac{225}{125}=1+\dfrac{5}{3}=\dfrac{8}{3}\)

x = 42

y = 12

x = 42, y = 12;

=(25+25)+(43+57)+(32+48)+(84+16)

=50+100+80+100

=330