8x1=8 

8x2=16

8x3=24

8x4=32

8x5=40

8x6=48

8x7=56

8x8=64

8x9=72

8x10=80

8x1=8

8x2=16

8x3=24

8x4=32

8x5=40

8x6=48

8x7=56

8x8=64

8x9=72

8x10=80

minh nhanh nhat k nha

Sắp xếp hai đa thức theo lũy thừa giảm dần của biến rồi sau đó thực hiện phép tính:

8x1=8

8x2=16

8x3=24

8x4=32

8x5=40

8x6=48

8x7=56

8x8=64

8x9=72

8x10=80

8 x 1 = 8

8 x 2 = 16

8 x 3 = 24

8 x 4 = 32

8 x 5 = 40 

8 x 6 = 48

8 x 7 = 56

8 x 8 = 64

8 x 9 = 72

8 x 10 = 80

thanks

21:

a: \(f\left(x\right)=4x^4-x^3-4x^2+x-1\)

\(g\left(x\right)=x^4+4x^3+x-5\)

b: f(x)-g(x)

=4x^4-x^3-4x^2+x-1-x^4-4x^3-x+5

=3x^4-5x^3-4x^2+4

f(x)+g(x)

=4x^4-x^3-4x^2+x-1+x^4+4x^3+x-5

=5x^4+3x^3-4x^2+2x-6

c: g(-1)=1-4-1-5=-9

\(\dfrac{5}{8}\) x 4 + \(\dfrac{5}{8}\) x \(\dfrac{4}{5}\)

= \(\dfrac{5}{8}\) x (\(4\) + \(\dfrac{4}{5}\) )

= \(\dfrac{5}{8}\) x \(\dfrac{24}{5}\) = 3

\(\dfrac{5}{8}\times4+\dfrac{5}{8}\times\dfrac{4}{5}\)
\(=\dfrac{5}{8}\times\left(4+\dfrac{4}{5}\right)\)
\(=\dfrac{5}{8}\times\dfrac{24}{5}\)
\(=\dfrac{24}{8}\)
\(=3\)

\(\frac{7}{9}+\frac{6}{7}\times\frac{4}{5}=\frac{7}{9}+\frac{24}{35}=\frac{361}{315}\)

\(\frac{21}{23}+\frac{4}{5}:\frac{6}{8}=\frac{21}{23}+\frac{16}{15}=\frac{548}{345}\)

\(\frac{5}{8}\times\frac{4}{9}:\frac{2}{3}=\frac{5}{18}:\frac{2}{3}=\frac{5}{12}\)

\(\frac{7}{12}+\frac{5}{6}-\frac{21}{24}=\frac{14}{24}+\frac{20}{24}-\frac{21}{24}=\frac{11}{24}\)

b, 

    \(\frac{21}{23}+\frac{4}{5}:\frac{6}{8}=\frac{21}{23}+\frac{4}{5}.\frac{8}{6}=\frac{21}{23}+\frac{16}{15}=1\frac{338}{345}\)

c,

    \(\frac{5}{8}.\frac{4}{9}.\frac{3}{2}=\frac{5}{12}\)

d,

    \(\frac{7}{12}+\frac{5}{6}-\frac{21}{24}=\frac{14}{24}+\frac{20}{24}-\frac{21}{24}=\frac{13}{24}\)

chán thật 

=6/5x{3/8+5/8}-4/5

=6/5x1-4/5

=6/5-4/5=2/5

ta có A = 6/5( 3/8+5/8) - 4/5 

           = 6/5*1 - 4/5 

           =  6/5 - 4/5 

           = 2/5

      Vậy A = 2/5