恆等式與因式分解4(請盡快回答)

(6+5)(5-6c)=11(5-6c)=55-66c
(5c-7)(7-x)=35c-5cx-49+7x
(x+2)(x-2)=x²-2x+2x-4=x²-4
(5x+2x)(5-2x)=(7x)(5-2x)=35x-14x²=-14x²+35x
(x+3)(x-3)=x²-3x+3x-9=x²-9
(4x-1)(1+4x)=4x+16x²-1-4x=16x²-1

1.(x+3)(x-3)
=x²-3²
=x²-9

2.(4x-1)(1+4x)
=(4x-1)(4x+1)
=(4x)²-1²
=16x²-1

3.(5x+2x)(5-2x)
=25x-10x²+10x-4x²
=-10x²-4x²+25x+10x
=-14x²+30x
=2x(-7x+15)

4.(x+2)(x-2)
=x²-2²
=x²-4

5.(6+5)(5-6c)
=11(5-6c)
=55-66c

6.(5c-7)(7-x)
=35c-5cx-49+7x

2014-11-28 19:28:38 補充：
3.(5x+2x)(5-2x)
=7x(5-2x)
=35x-14x²
=7x(5-2x)

1.
(x+3)(x-3)
=x^2 -9

2.
(4x-1)(1+4x)
=(4x-1)(4x+1)
=16x^2 -1

3.
(5x+2x)(5-2x)
=(7x)(5-2x)
=35x-14x^2

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

5.
(6+5)(5-6c)
=11(5-6c)
=55-66c

6.
(5c-7)(7-x)
=35c-5cx-49+7x
=35c-5cx+7x-49