a) ( x - 5 )( 2x + 3 ) + 2x( 1 - x )

= 2x² - 7x - 15 + 2x - 2x²

= -5x - 15

= -5( x + 3 )

b) ( 3x - 5 )² - ( x + 5 )( 5 - x ) - 5/2( -2x )²

= 9x² - 30x + 25 + ( x + 5 )( x - 5 ) - 5/2.4x²

= 9x² - 30x + 25 + x² - 25 - 10x²

= -30x

c) ( 3x + 2 )( 4 - 6x + 9x² ) - 3x( 3x - 2 )² + 12( -2/3 - 3x² )

= ( 3x )³ + 2³ - 3x( 9x² - 12x + 4 ) - 8 - 36x²

= 27x³ + 8 - 27x³ + 36x² - 12x - 8 - 36x²

= -12x

a, \(\left(x-5\right)\left(2x+3\right)+2x\left(1-x\right)=2x^2+3x-10x-15+2x-2x^2=-5x-15\)

b, \(\left(3x-5\right)^2-\left(x+5\right)\left(5-x\right)-\frac{5}{2}\left(-2x\right)^2\)

\(=9x^2-30x+25-\left(5x-x^2+25-5x\right)-\frac{5}{2}\left(4x^2\right)\)

\(=-30x\)

a. \(2x\left(x-5\right)-\left(x-2\right)^2-\left(x+3\right)\left(x-3\right)\)

\(=2x^2-10x-x^2+4x-4-x^2+9\)

\(=-6x+5\)

b. \(\left(x+1\right)^2+3\left(x-5\right)\left(x+5\right)-\left(2x-1\right)^2\)

\(=x^2+2x+1+3x^2-75-4x^2+4x-1\)

\(=6x-75\)

c. \(2x\left(x-7\right)-\left(x+3\right)\left(x-2\right)-\left(x+4\right)\left(x-4\right)\)

\(=2x^2-14x-x^2-x+6-x^2+16\)

\(=-15x+22\)

d. \(\left(x+3\right)\left(x-3\right)-\left(x+5\right)\left(x-1\right)-\left(x-4\right)^2\)

\(=x^2-9-x^2-4x+5-x^2+8x-16\)

\(=-x^2+4x-20\)

Bài làm:

a) \(2x\left(x-5\right)-\left(x-2\right)^2-\left(x+3\right)\left(x-3\right)\)

\(=2x^2-10x-x^2+4x-4-x^2+9\)

\(=-6x+5\)

b) \(\left(x+1\right)^2+3\left(x-5\right)\left(x+5\right)-\left(2x-1\right)^2\)

\(=x^2+2x+1+3x^2-75-4x^2+4x-1\)

\(=6x-75\)

c) \(2x\left(x-7\right)-\left(x+3\right)\left(x-2\right)-\left(x+4\right)\left(x-4\right)\)

\(=2x^2-14x-x^2-x+6-x^2+16\)

\(=-15x+22\)

d) \(\left(x+3\right)\left(x-3\right)-\left(x+5\right)\left(x-1\right)-\left(x-4\right)^2\)

\(=x^2-9-x^2-4x+5-x^2+8x-16\)

\(=-x^2-4x-20\)

đầy đủ từng bước nhé

\(a,2x\left(x-5\right)-\left(x-2\right)^2-\left(x+3\right)\left(x-3\right)\)

\(=2x^2-10x-\left(x^2-4x+4\right)-\left(x^2-9\right)\)

\(=2x^2-10x-x^2+4x-4-x^2+9\)

\(=\left(2x^2-x^2-x^2\right)+\left(4x-10x\right)+\left(9-4\right)\)

\(=0-6x+5=5-6x\)

\(b,\left(x+1\right)^2+3\left(x-5\right)\left(x+5\right)-\left(2x-1\right)^2\)

\(=\left(x^2+2x+1\right)+3\left(x^2-25\right)-\left(4x^2-4x+1\right)\)

\(=x^2+2x+1+3x^2-75-4x^2+4x-1\)

\(=\left(x^2+3x^2-4x^2\right)+\left(2x+4x\right)+\left(1-1-75\right)\)\(=6x-75\)

\(c,2x\left(x-7\right)-\left(x+3\right)\left(x-2\right)-\left(x+4\right)\left(x-4\right)\)

\(=2x^2-14x-\left(x+2\right)\left(x-2\right)-x+2-\left(x+4\right)\left(x-4\right)\)

\(=2x^2-14x-x^2+4-x+2-x^2+16\)

\(=\left(2x^2-x^2-x^2\right)+\left(-14x-x\right)+\left(16+2+4\right)\)

\(=0-15x+22=22-15x\)

\(d,\left(x+3\right)\left(x-3\right)-\left(x+5\right)\left(x-1\right)-\left(x-4\right)^2\)

\(=\left(x+3\right)\left(x-3\right)-\left(x+1\right)\left(x-1\right)-4\left(x-1\right)-\left(x-4\right)^2\)

\(=x^2-9-x^2+1-4x+4-\left(x^2-8x+16\right)\)

\(=\left(x^2-x^2\right)-4x+\left(4+1-9\right)-x^2+8x-16\)

\(=-4x-4-x^2+8x-16=-x^2+\left(8x-4x\right)-\left(16+4\right)\)

\(=-x^2+4x-20\)

^{\(\left(3x-1\right)^2+2\left(9x^2-1\right)+\left(3x+1\right)^2\)}

\(=9x^2-6x+1+18x^2+2+9x^2+6x+1\)

\(=36x^2+4\)

\(\left(x^2-1\right)\left(x+3\right)-\left(x-3\right)\left(x^3+3x+9\right)\)

\(=x^3+3x^2-x+3-\left(x^4+3x^2+9x-3x^3-9x-27\right)\)

\(=x^3+3x^2-x+3-x^4-3x^2-9x+3x^3+9x-27\)

\(=\left(3x^2-3x^2\right)+\left(9x-9x\right)-x-\left(27-3\right)+x^3-x^4+3x^3\)

\(=-x-24+x^3-x^4+3x^3\)

\(\left(x+4\right)\left(x-4\right)-\left(x-4\right)^2\)

\(=x^2-16-\left(x-4\right)^2\)

\(=x^2-16-x^2+8x-16\)

\(=8x-32\)

\(=\frac{1}{x+1}-\frac{1}{x+2}+\frac{1}{x+2}-\frac{1}{x+3}+\frac{1}{x+3}-\frac{1}{x+4}+\frac{1}{x+4}-\frac{1}{x+5}\)

1/ (x+1)(x+2) +1/ (x+2)(x+3) +1/ (x+3)(x+4) +1/ (x+4)(x+5)

=1/x+1 -1/x+2 +1/x+2 -1/x+3 +1/x+3 -1/x+4 +1/x+4 -1/x+5

=1/x+1 -1/x+5

=4/(x+1)(x+5)

\(=\frac{1}{x+1}-\frac{1}{x+2}+\frac{1}{x+2}-\frac{1}{x+3}+\frac{1}{x+3}-\frac{1}{x+4}+\frac{1}{x+4}-\frac{1}{x+5}\)

\(=\frac{1}{x+1}-\frac{1}{x+5}=\frac{x+5-x-1}{\left(x+1\right)\left(x+5\right)}=\frac{4}{\left(x+1\right)\left(x+5\right)}\)

CÂU NÀY RỒI

MÌNH TRẢ LỜI Ở DƯỚI ĐÓ

a)  (x-4)(x+4)x-(x²+1)(x²-1)=(x²-16)x-(x⁴-1)=x³-16x-x⁴+1

b)  (y-3)(y+3)(y²+9)-(y²+2)(y²-2)=(y²-9)(y²+9)-(y⁴-4)=y⁴-81-y⁴+4=-77

c)  x(x+1/2)-(2x-1)(x+3/4)=x²+1/2x-2x²+3/2x-x-3/4=-x²+x-3/4

em moi hoc lop 5

\(\left(x-3\right)\left(x+3\right)-\left(x+5\right)\left(x-1\right)-\left(x-4\right)^2\)

\(=x^2-9-x^2-4x+5-x^2+8x-16\)

\(=-x^2+4x-20\)