(5x -1) + 2( 1 -5x) (4+ 5x ) + (5x + 4)2
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P = (5x − 1) + 2(1 − 5x)(4 + 5x) + (5x+4)\(^2\)
= 5x – 1 + (2 – 10x).( 4+ 5x) + (5x+4)\(^2\)
= 5x – 1 + 8 + 10x – 40x – 50x\(^2\) + 25x\(^2\) + 40x + 16
= ( - 50x\(^2\) + 25x\(^2\) ) + ( 5x + 10x – 40x + 40x) + ( - 1+ 8 + 16 )
= -25x\(^2\) + 15x + 23
\(\left(5x-1\right)^2+2\left(1-5x\right)\left(4+5x\right)+\left(5x+4\right)^2\)
\(=\left(5x-1\right)^2-2\left(5x-1\right)\left(5x+4\right)+\left(5x+4\right)^2\)
\(=\left[\left(5x-1\right)-\left(5x+4\right)\right]^2\)
\(=\left(5x-1-5x-4\right)^2\)
\(=\left(-5\right)^2\)
\(=25\)
\(P=\left(5x-1\right)+2\left(1-5x\right)\left(4+5x\right)+\left(5x+4\right)^2\)
\(P=5x-1+\left(2-10x\right)\left(4+5x\right)+\left(5x+4\right)^2\)
\(P=5x-1+8+10x-40x-50x^2+25x^2+40x+16\)
\(P=\left(25x^2-50x^2\right)+\left(5x+10x-40x+40x\right)+\left(-1+8+16\right)\)
\(P=-25x^2+15x+23\)
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
(**** )
Lời giải:
Tại $x=4$ thì:
\(A=5(x^5-x^4+x^3-x^2+x-1)-1\)
\(=(x+1)(x^5-x^4+x^3-x^2+x-1)-1=x^6+1-1=x^6\)
\(=4^6=4096\)
rút gọn nha
sửa đề : \(\left(5x-1\right)^2+2\left(1-5x\right)\left(5x+4\right)+\left(5x+4\right)^2\)
\(=\left(5x-1\right)^2-2\left(5x-1\right)\left(5x+4\right)+\left(5x+4\right)^2\)
\(=\left(5x-1-5x-4\right)^2=\left(-5\right)^2=25\)