x=7

=>x+1=8

=> A= x^15 - 8x^14 + 8x^13 - 8x^12 +....- 8x^2 + 8x - 5 

=x¹⁵-(x+1)x¹⁴+(x+1)x¹³-(x+1)x¹²+...-(x+1)x²+(x+1)x-5

=x¹⁵-x¹⁵-x¹⁴+x¹⁴+x¹³-x¹³-x¹²+...-x³-x²+x²+x-5

=x-5

=>A=7-5=2

Vậy A=2 khi x=7

\(B=x^{15}-8x^{14}+8x^{13}-8x^{12}+...+8x-5\)

\(=x^{15}-\left(x+1\right)x^{14}+\left(x+1\right)x^{13}-\left(x+1\right)x^{12}+...+\left(x+1\right)x-x+2\)

\(=x^{15}-x^{15}-x^{14}+x^{14}+x^{13}-x^{13}-x^{12}+...+x^2+x-x+2\)

\(=2\)

Ta có B = 7¹⁵ - 8.7¹⁴ + 8.7¹³ - 8.7¹² + ... - 8.7² + 8.7 – 5 

             = 7¹⁵ - 8.(7¹⁴ - 7¹³ + 7¹² - .... + 7² - 7) - 5

Đặt C = 7¹⁴ - 7¹³ + 7¹² - .... + 7² - 7

=> 7C = 7¹⁵ - 7¹⁴ + 7¹³ - .... + 7³ - 7²

Lấy 7C cộng C theo vế ta có : 

7C + C = ( 7¹⁵ - 7¹⁴ + 7¹³ - .... + 7³ - 7²) + (7¹⁴ - 7¹³ + 7¹² - .... + 7² - 7)

  8C = 7¹⁵ - 7

=> C = \(\left(7^{15}-7\right).\frac{1}{8}\)

Khi đó B = \(7^{15}-8.\left(7^{15}-7\right).\frac{1}{8}-5=7^{15}-7^{15}+7-5=2\)

Ta có: \(x=7\)\(\Rightarrow x+1=8\)

\(B=x^{15}-\left(x+1\right)x^{14}+\left(x+1\right)x^{13}-........-\left(x+1\right)x^2+\left(x+1\right)x-5\)

\(=x^{15}-x^{15}-x^{14}+x^{14}+x^{13}-......-x^3-x^2+x^2+x-5\)

\(=x-5=7-5=2\)

Với x = 7 ta có 8 = x + 1

Thay 8 = x + 1 vào biểu thức B ta có  \(B=x^{15}-\left(x+1\right)x^{14}+\left(x+1\right)x^{13}-\left(x+1\right)x^{12}+...-\left(x+1\right)x^2+\left(x+1\right)x-5\)

   \(=x^{15}-x^{15}-x^{14}+x^{14}+x^{13}-x^{13}-x^{12}+...-x^3-x^2+x^2+x-5\)

   \(=x-5\)

  Thay x = 7 vào biểu thức B đã thu gọn ta được B = 7 - 5 = 2

   Vậy B = 2

Ta có : \(x=7\Rightarrow x+1=8\)

\(B=x^{15}-\left(x+1\right)x^{14}+\left(x+1\right)^{13}-\left(x+1\right)x^{12}+...+\left(x+1\right)x-x+2\)

\(=x^{15}-x^{15}-x^{14}+x^{14}+x^{13}-x^{13}-x^{12}+...+x^2+x-x+2=2\)

Vì x=8=>x+1=8 thay vào B ,Ta có:

B = x¹⁵ - 8x¹⁴ + 8x¹³ - 8x¹² + ... - 8x² + 8x – 5 với x = 7

=x¹⁵-(x+1)x¹⁴ +(x+1)x¹³-(x+1)x¹²+...-(x+1)x²+(x+1)x-5

=x¹⁵-x¹⁵-x¹⁴+x¹⁴+...-x³-x²+x²+x-5

=x-5

Thay x=7 ,ta đc:

7-5=2

Vậy B=2

x = 7 => 8 = x + 1

Thế vào B ta được

B = x¹⁵ - ( x + 1 )x¹⁴ + ( x + 1 )x¹³ - ( x + 1 )x¹² - ... - ( x + 1 )x² + ( x + 1 )x - 5

B = x¹⁵ - ( x¹⁵ + x¹⁴ ) + ( x¹⁴ + x¹³ ) - ( x¹³ + x¹² ) - ... - ( x³ + x² ) + ( x² + x ) - 5

B = x¹⁵ - x¹⁵ - x¹⁴ + x¹⁴ + x¹³ - x¹³ - x¹² + ... - x³ - x² + x² + x - 5

B = x - 5

B = 7 - 5 = 2

\(B=x^{15}-8x^{14}+8x^{13}-8x^{12}+...+8x-5\)

\(=x^{15}-\left(x+1\right)x^{14}+\left(x+1\right)x^{13}-\left(x+1\right)x^{12}+...+\left(x+1\right)x-x+2\)

\(=x^{15}-x^{15}-x^{14}+x^{14}+x^{13}-x^{13}-x^{12}+...+x^2+x-x+2\)

\(=2\)

Từ \(x=7\Rightarrow x+1=8\) thay vào B ta được :

\(B=x^{15}-\left(x+1\right)x^{14}+\left(x+1\right)x^{13}-\left(x+1\right)x^{12}+...-\left(x+1\right)x^2+\left(x+1\right)x-5\)

\(=x^{15}-x^{15}-x^{14}+x^{14}+......-x^3-x^2+x^2+x-5\)

\(=x-5=7-5=2\)

Vậy B = 2

\(B=x^{15}-8x^{14}+8x^{13}-8x^{12}+...+8x-5\)

\(=x^{15}-\left(x+1\right)x^{14}+\left(x+1\right)x^{13}-\left(x+1\right)x^{12}+...+\left(x+1\right)x-x+2\)

\(=x^{15}-x^{15}-x^{14}+x^{14}+x^{13}-x^{13}-x^{12}+...+x^2+x-x+2\)

\(=2\)

tao huy dz

=231313131313131313131221333t6543311

Ta có:

x=7=>x+1=8

A=x¹⁵-(x+1)¹⁴+(x+1)x¹³-(x+1)x¹²+...-(x+1)x²+(x+1)x-5=x¹⁵-x¹⁵-x¹⁴+x¹⁴+x¹³-x¹³-x¹²+...-x³-x²+x²+x-5=7-5=2

Vậy A=2

x=7=>x+1=8

B=x¹⁵-8x¹⁴+8x¹³-8x¹²+....-8x²+8x-5

=x¹⁵-(x+1)x¹⁴+(x+1)x¹³-(x+1)x¹²+...-(x+1)x²+(x+1)x-5

=x¹⁵-x¹⁵-x¹⁴+x¹⁴+x¹³-x¹³+x¹²+...-x³-x²+x²+x-5

=x-5

=7-5

=2

Vậy B=2

\(B=x^{15}-8x^{14}+8x^{13}-8x^{12}+...+8x-5\)

\(=x^{15}-\left(x+1\right)x^{14}+\left(x+1\right)x^{13}-\left(x+1\right)x^{12}+...+\left(x+1\right)x-x+2\)

\(=x^{15}-x^{15}-x^{14}+x^{14}+x^{13}-x^{13}-x^{12}+...+x^2+x-x+2\)

\(=2\)

\(B=x^{15}-8x^{14}+8x^{13}-8x^{12}+...+8x-5\)

\(=x^{15}-\left(x+1\right)x^{14}+\left(x+1\right)x^{13}-\left(x+1\right)x^{12}+...+\left(x+1\right)x-x+2\)

\(=x^{15}-x^{15}-x^{14}+x^{14}+x^{13}-x^{13}-x^{12}+...+x^2+x-x+2\)

\(=2\)