a: =8-6=2

b: =30(55+46-1)=3000

a) 8 + 2. ( − 3 ) = 8 + ( - 6 ) = 8 - 6 = 2 
b) 30.55 + 30.46 – 2.15

= 30 . 55 + 30 . 46 - 30

= 30 . ( 55 + 46 - 1 )

= 30 . 100 = 3000
c) 4.15 − [ 144 − ( 12 − 4 )² ]

= 4 . 15 - [ 144 - 8² ]

= 4 .15 - [ 144 - 64 ] 

= 60 - 80

= - 20

\(\dfrac{5}{12}+\dfrac{3}{16}=\dfrac{5\cdot4+3\cdot3}{48}=\dfrac{29}{48}\)

\(\dfrac{4}{15}-\dfrac{2}{9}=\dfrac{4\cdot3-2\cdot5}{45}=\dfrac{2}{45}\)

a) \(\dfrac{5}{12}+\dfrac{3}{16}=\dfrac{20}{48}+\dfrac{9}{48}=\dfrac{29}{48}\)

b) \(\dfrac{4}{15}-\dfrac{2}{9}=\dfrac{12}{45}-\dfrac{10}{45}=\dfrac{2}{45}\)

\(a,\dfrac{5}{12}+\dfrac{3}{16}=\dfrac{20}{48}+\dfrac{9}{48}=\dfrac{29}{48}\)

\(b,\dfrac{4}{15}-\dfrac{2}{9}=\dfrac{12}{45}-\dfrac{10}{45}=\dfrac{12-10}{45}=\dfrac{2}{45}\)

\(a,x^2\left(5x^3-2x+3\right)=5x^5-2x^3+3x^2\\ b,\left(3x+2\right)\left(5x-3\right)=5x\left(3x+2\right)-3\left(3x+2\right)=15x^2+10x-9x-6=15x^2+x-6\\ c,\left(5x+y\right)^2=25x^2+10xy+y^2\)

a: \(-15-\left(-13+30\right)\)

\(=-15+13-30\)

\(=\left(-15-30\right)+13\)

=-45+13

=-32

b: \(225-150:\left(30+3^2\cdot5\right)\)

\(=225-150:\left(30+9\cdot5\right)\)

\(=225-150:75\)

=225-2

=223

c: \(18\cdot64+18\cdot36-1200\)

\(=18\left(64+36\right)-1200\)

\(=18\cdot100-12\cdot100\)

\(=6\cdot100=600\)

d: \(80-\left[130-\left(12-4\right)^2\right]\)

\(=80-130+\left(12-4\right)^2\)

\(=-50+8^2=64-50=14\)

a) 4x^2 ( 5x^3 - 2x + 3 )

= 20x^5 - 8x^3 + 12x^2

b) ( 2x + 5 ) ( 3x - 2 )

= 6x^2 - 4x + 15x - 10

= 6x^2 + 11x - 10

c) ( 5x + y )^2

= ( 5x )^2 + 2 . 5x . y + y^2

= 24x^2 + 10xy + y^2

a)-1-2-3-4-5-6-....-80

=(-1)+(-2)+(-3)+(-4)+(-5)+(-6)+...+(-80)

Khoảng cách giữa các số:(-1)-(-2)=1

Tổng các số hạng:(-1)-(-80)+1=80 số

Tổng:[(-1)+(-80)].80:2= -3240

=>-1-2-3-4-5-6+......-80=-3240

b,1-2+3-4+5-6+......+2021-2022

=(1-2)+(3-4)+(5-6)+...+(2021-2022)

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

Tổng số cặp là:

(2022-1+1):2=1011 cặp

-1.1011=-1011

=>1-2+3-4+5-6+......+2021-2022= -1011

c, Đề bài sai

d,-4-8-12-16-.......-2020

=-4+(-8)+(-12)+(-16)+...+(-2020)

Khoảng cách giữa các số:-4-(-8)=4

Tổng các số hạng:[-4-(-2020]:4+1=505 số

Tổng:[-4+(-2020)].505:2=-511060

=>-4-8-12-16-.......-2020=-511060

Mọi người giúp mình với ạ! Thank you everyone!

a/=68

a) 125 : 25 + 12 . 4      c) 2680 + [ 10 . ( 4³ -54 ) : 5² + 2⁴]

= 5 + 48                        = 2680 + [ 10 . ( 64 - 54 ) : 25 + 16]

= 53                              = 2680 + [ 10 . 10 : 25 + 16]

                                     = 2680 + [ 100 : 25 + 16]

                                     = 2680 + [ 4 + 16 ]

                                     = 2680 + 20

                                     = 2700

a/ 125 : 25 + 12 . 4

=5+48

=53

c/ 2680 + [ 10 . ( 4³ - 54 ) : 5² + 2⁴ ]

=2680 +  [ 10 . 10 : 25 + 16 ]

= 2680 + 20

=2700

b/ 25 - ( 62 - 75 ) + ( - 38 )

= 25 - (- 13) + (- 38) 

=25 + 13 + (- 38)

=38 + (-38)

=0

Ta có: \(\sqrt{75}-2\cdot\sqrt{12}+\sqrt{3}\)

\(=5\sqrt{3}-2\cdot2\sqrt{3}+\sqrt{3}\)

\(=6\sqrt{3}-4\sqrt{3}\)

\(=2\sqrt{3}\)