a)\(=12\times3+4\times12+12\times3=12\times\left(3+4+3\right)=12\times10=120\)

b)\(=25\times7-25\times2-3\times25-2\times25=25\times\left(7-2-3-2\right)=0\)

A) 12x3+4x12+36

=12x3+4x12+12x3

=12x(3+4+3)

=120

3/5

3/5

\(\dfrac{3}{5}\)

a: =-1,93+0,895=-1,035

b: =-1,6+0,93-0,131=-1,6+0,799=-0,801

c: =-3.87+9,07-2,8=5,2-2,8=2,4

a: \(A=\dfrac{5}{7}-\dfrac{2}{7}+\dfrac{8}{11}+\dfrac{3}{11}+\dfrac{1}{2}=\dfrac{3}{7}+\dfrac{1}{2}+1=\dfrac{6+7+14}{14}=\dfrac{27}{14}\)

b: \(B=\dfrac{11}{17}+\dfrac{6}{17}-\dfrac{8}{19}-\dfrac{30}{19}+\dfrac{-3}{4}=1-2-\dfrac{3}{4}=-1-\dfrac{3}{4}=-\dfrac{7}{4}\)

c: \(C=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{49}-\dfrac{1}{50}=\dfrac{49}{50}\)

a) \(3119\cdot121-3119\cdot11\cdot11\\ =3119\left(121-11\cdot11\right)\\ =3119\left(121-121\right)\\ =3119\cdot0=0\)

b) \(24\cdot\left(123+87\right)+\left(87+123\right)\cdot76\\ =\left(123+87\right)\left(24+76\right)\\ =210\cdot100=21000\)

a: \(232-\left(581+132-331\right)\)

\(=232-581-132+331\)

\(=\left(232-132\right)+\left(-581+331\right)\)

\(=100-250\)

=-150

b: \(\left[12+\left(-57\right)\right]-\left[-57-\left(-12\right)\right]\)

\(=12+\left(-57\right)+57+\left(-12\right)\)

\(=\left(12-12\right)+\left(57-57\right)\)

=0+0

=0

`28 xx 7,32 - 7,32 : 0,125`

`= 28 xx 7,32 - 7,32 xx8`

`= 7,32 xx(28-8)`

`= 7,32 xx20`

`=146,4`

a: =382-282+531-331

=100+200=300

b: =(7-8)+(9-10)+...+(2009-2010)

=(-1)+(-1)+....+(-1)

=-1002

c: =-(1+2+3+...+2009+2010)

=-2010*2011/2=-2021055

Bài 1: 

a: \(\dfrac{25}{42}-\dfrac{20}{63}=\dfrac{75-40}{126}=\dfrac{35}{126}=\dfrac{5}{18}\)

b: \(\dfrac{9}{20}-\dfrac{13}{75}-\dfrac{1}{6}=\dfrac{135}{300}-\dfrac{52}{300}-\dfrac{50}{300}=\dfrac{33}{300}=\dfrac{11}{100}\)