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

C

C

mình nhầm tí.

\(=\left(2x-3-2x-5\right)^2=\left(-8\right)^2=64\) nha

a.(x+3)(x+1)

=x.(x+1)+3.(x+1)

=x²+x+3x+3

=x²+4x+3

b.(x+6)(2x-2)

=x.(2x-2)+6.(2x-2)

=2x²-2x+12x-12

=2x²+10x-12

\(1,=x\left(2x+3\right)-\left(2x+3\right)=2x^2+3x-2x-3=2x^2+x-3\\ 2,=\left(2x\right)^2-2.2.x.1+1^2=4x^2-4x+1\)

1. =2x²-2x+3x-3

2. (2x)²-2.2x.1+1²

=4x²-4x+1

1: \(x\left(3x-1\right)-2x\left(x-1\right)-\left(x-2\right)^2\)

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

\(=x^2+x-x^2+4x-4=5x-4\)

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

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

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

\(=x^2+4x-6\)

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

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

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

5:

a: (2x-5)(2x+5)=4x^2-25

b: (3x-5y)(3x+5y)=9x^2-25y^2

c: (3x+7y)(3x-7y)=9x^2-49y^2

d: (2x-1)(2x+1)=4x^2-1

4:

a: 2003*2005=(2004-1)(2004+1)=2004^2-1<2004^2

b: 8(7^2+1)(7^4+1)(7^8+1)

=1/6*(7-1)(7+1)(7^2+1)(7^4+1)(7^8+1)

=1/6(7^2-1)(7^2+1)(7^4+1)(7^8+1)

=1/6(7^16-1)<7^16-1

5:

a: (2x-5)(2x+5)=4x^2-25

b: (3x-5y)(3x+5y)=9x^2-25y^2

c: (3x+7y)(3x-7y)=9x^2-49y^2

d: (2x-1)(2x+1)=4x^2-1

mik chỉ biết bài 5 thôi !