A = 26² - 24² = (26 - 24)(26 + 24) = 2.50 = 100

B = 27² - 25² = (27 - 25)(27 + 25) = 2.52 = 104

\(A=26^2-24^2\)

\(A=\left(26-24\right)\left(26+24\right)\)

\(A=2.50\)

\(B=27^2-25^2\)

\(B=\left(27-25\right)\left(27+25\right)\)

\(B=2.52\)

\(2.50< 2.52\)

\(< =>A< B\)

A= x³- 9x²+ 27x- 27 tại x=13, ta có: 

A= 13³- 9.13²+ 27.13- 27

A= 13³- 3.3.13²+ 3.3³.13- 3³

A= (13- 3)³

A= 10³

^{A= 1000}

^{Vậy đa thức A tại x= 13 có kết quả bằng 1000}

`A  = x^3 - 9x^2 +27x - 27`

`->A = x^3 - 3 . x^2 . 3 + 3 . x . 3^2 -3^3`

`->A = (x-3)^3`

`->A = (13-3)^3`

`->A=10^3=10 000`

Vậy `A=10 000`

a, \(\dfrac{27}{8x^3-1}:\dfrac{3}{2x-1}\)

\(=\dfrac{27}{\left(2x-1\right)\left(4x^2+2x+1\right)}.\dfrac{2x-1}{3}\)

\(=\dfrac{9}{4x^2+2x+1}\)

b, \(\dfrac{8x^3+36x^2+54x+27}{2x+3}=\dfrac{\left(2x+3\right)^3}{2x+3}=\left(2x+3\right)^2\)

a: \(\left(a-2b\right)^2-4b^2\)

\(=\left(a-2b\right)^2-\left(2b\right)^2\)

=(a-2b-2b)(a-2b+2b)

=a(a-4b)

b: \(\left(a-b\right)^2-c^2=\left(a-b-c\right)\left(a-b+c\right)\)

c: \(\left(a+b\right)^2-4=\left(a+b\right)^2-2^2=\left(a+b+2\right)\left(a+b-2\right)\)

d: \(\left(a+3b\right)^2-9b^2\)

\(=\left(a+3b\right)^2-\left(3b\right)^2\)

=(a+3b-3b)(a+3b+3b)=a(a+6b)

e: \(\left(x-3\right)^3-27\)

\(=\left(x-3-3\right)\left\lbrack\left(x-3\right)^2+3\left(x-3\right)+9\right\rbrack\)

\(=\left(x-6\right)\left(x^2-6x+9+3x-9+9\right)=\left(x-6\right)\left(x^2-3x+9\right)\)

f: \(\left(x+1\right)^3-125\)

\(=\left(x+1-5\right)\left\lbrack\left(x+1\right)^2+5\left(x+1\right)+25\right\rbrack\)

\(=\left(x-4\right)\left(x^2+2x+1+5x+5+25\right)=\left(x-4\right)\left(x^2+7x+31\right)\)

dấu ^ là mũ nha mn

D = 34² + 2.34.66 + 66² = (34 + 66)² = 100² = 10000

^_^                  

a)  4 7 + 3 4 + 2 7 + 5 4 + 1 7 = 4 7 + 2 7 + 1 7 + 3 4 + 5 4 = 3

b)  − 5 7 + 3 4 + − 1 5 + − 2 7 + 1 4 = − 5 7 + − 2 7 + 3 4 + 1 4 + − 1 5 = − 1 + 1 + − 1 5 = − 1 5