a)=-100

  =-144

b)=-110

   =-2055

c)=-600

   =-180

-100

-144

-110

-2055

a)-50

b)-88

c)0

d)-22

\(=\dfrac{12}{25}+\dfrac{15}{25}+\dfrac{12}{25}=\left(\dfrac{12}{25}+\dfrac{12}{25}\right)+\dfrac{15}{25}=\dfrac{24}{25}+\dfrac{15}{25}=\dfrac{39}{25}\)

= 39/25

\(\dfrac{39}{25}\)

\(0< a< \dfrac{pi}{2}\)

=>\(sina>0\)

\(sin^2a+cos^2a=1\)

=>\(sin^2a=1-\dfrac{16}{25}=\dfrac{9}{25}\)

=>\(sina=\dfrac{3}{5}\)

\(sin2a=2\cdot sina\cdot cosa=2\cdot\dfrac{3}{5}\cdot\dfrac{4}{5}=\dfrac{24}{25}\)

=>Chọn B

\(\left(-25\right).45-25.67+25.12\)

\(=25\left(-45-67+12\right)\)

\(=25\left(-100\right)\)

\(=-2500\)

\(\left(-25\right).45-25.67+25.12\)

\(=25\left(-45-67+12\right)\)

\(=25.\left(-100\right)\)

\(=\left(-2500\right)\)

12.( -131-25)+131.( 12+25)

= -12.131-12.25+131.12+131.25

= -12.25+131.25

= 25.( 131-12)

= 25.119

= 2975

#Châu's ngốc

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

a) (12 + 8) x 4 = 20 x 4

                         = 80

12 + 8 x 4 = 12 + 32

                         = 44

b) 25 + 75 : 5 = 25 + 15

                         = 40

(25 + 75) : 5 = 100 : 5

                         = 20

=\(\frac{12}{25}.\left(-38,2-61,8\right)\)

=\(\frac{12}{25}.\left(-100\right)\)

=\(-48\)

= 12/25 . (-38,2 - 61,8)

=  12/25 . (-100)

=  -48