Rút gọn biểu thức:
P = (5x - 1) + 2(1 - 5x)(4 + 5x) + (5x + 4)2
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\(P=\left(5x-1\right)+2\left(1-5x\right)\left(4+5x\right)+\left(5x+4\right)^2\)
\(P=5x-1+\left(2-10x\right)\left(4+5x\right)+\left(5x+4\right)^2\)
\(P=5x-1+8+10x-40x-50x^2+25x^2+40x+16\)
\(P=\left(25x^2-50x^2\right)+\left(5x+10x-40x+40x\right)+\left(-1+8+16\right)\)
\(P=-25x^2+15x+23\)
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
(**** )
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:
\(\left(5x-1\right)^2+2.\left(1-5x\right).\left(4+5x\right)+\left(5x+4\right)^2\)
\(=\left(5x-1\right)^2-2.\left(5x-1\right).\left(5x+4\right)+\left(5x+4\right)^2\)
\(=\left(5x-1-5x-4\right)^2\)
\(=\left(-5\right)^2\)
\(=25\)
p = ( 5x -1 ) +2 . (5x+4)2
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