\(P=\left(5x-1\right)+2\left(1-5x\right)\left(4+5x\right)+\left(5x+4\right)^2\)

\(P=5x-1+\left(2-10x\right)\left(4+5x\right)+\left(5x+4\right)^2\)

\(P=5x-1+8+10x-40x-50x^2+25x^2+40x+16\)

\(P=\left(25x^2-50x^2\right)+\left(5x+10x-40x+40x\right)+\left(-1+8+16\right)\)

\(P=-25x^2+15x+23\)

P=(5x−1)+2(1−5x)(4+5x)+(5x+4)2

�=5�−1+(2−10�)(4+5�)+(5�+4)2P=5x−1+(2−10x)(4+5x)+(5x+4)2

�=5�−1+8+10�−40�−50�2+25�2+40�+16P=5x−1+8+10x−40x−50x2+25x2+40x+16

�=(25�2−50�2)+(5�+10�−40�+40�)+(−1+8+16)P=(25x2−50x2)+(5x+10x−40x+40x)+(−1+8+16)

�=−25�2+15�+23P=−25x2+15x+23

DỀ sai ròi kìa 

P = ( 5x- 1) ^2 + 2 ( 1 - 5x) .(4+5x) + (5x+4)^2

    = (5x- 1 )^2 - 2 ( 5x- 1).(5x+4) + (5x+4)^2

    =  (5x - 1 - 5x - 4) ^2 = ( - 5)^2 = 25

(**** )

để bn í ghi đúng mừ

 P = (5x - 1) + [(-2).(-1).(1-5x).(4+5x)] + (5x+4)^2
= (5x - 1).[(-1)-2.(-1).(4+5x)] + (25x^2+40x+16)
= [(5x - 1).(10x + 7)] + (25x^2+40x+16)
= 50x^2 +35x - 10x - 7 + 25x^2+40x+16
= 75x^2 + 65x -9

-25x^2+15x+23

   P = (5x − 1) + 2(1 − 5x)(4 + 5x) +  5 x + 4 2

      = 5x – 1 + (2 – 10x).( 4+ 5x) +  5 x + 4 2

      = 5x – 1 + 8 + 10x – 40x – 50 x 2  + 25 x 2  + 40x + 16

      = (- 50 x 2  + 25 x 2 )+ ( 5x + 10x – 40x + 40x) + (- 1+ 8 + 16)

      = -25 x 2  + 15x + 23

Sửa đề:

Cách 1:

\(\left(5x-1\right)^2+2.\left(1-5x\right).\left(4+5x\right)+\left(5x+4\right)^2\)

\(=\left(1-5x\right)^2+2.\left(1-5x\right).\left(5x+4\right)+\left(5x+4\right)^2\)

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

\(=5^2\)

\(=25\)

Cách 2:

\(\left(5x-1\right)^2+2.\left(1-5x\right).\left(4+5x\right)+\left(5x+4\right)^2\)

\(=\left(5x-1\right)^2-2.\left(5x-1\right).\left(5x+4\right)+\left(5x+4\right)^2\)

\(=\left(5x-1-5x-4\right)^2\)

\(=\left(-5\right)^2\)

\(=25\)