因式分解(二)要連式

According to the time record,The answer which was done by lai is correct.

2010-11-04 16:08:33 補充：
Also,he is the fastest ................

注:^2=2次方
計算方式:(a+b)^2=(a)^2+2(a)(b)+(b)^2
(a-b)^2=(a)^2-2(a)(b)+(b)^2



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

2.)25k^2-36
唔識做- -

3.)3-27y^2
=3(1-9y^2)
=3(1-3^2y^2)
=3(1+3y)(1-3y)

4.)8x^2-18
=2(4^2x^2-9^2)
=2(4x+9)(4x-9)

5.)x^2+14x+49
=(x)^2+2(x^2)(7)+(7)^2
=(x+7)^2

6.)2+16x+32x^2
唔識做

7.)-9x^2+30x-25
唔識做

記住要温書呀>v<!!!!

16-x²=4²-x²=(4-x)(4+x)
25k²-36=(5k)² - 6² =(5k-6)(5k+6)
3-27y²=3(1-9y²)=3(1-3y)(1+3y)
8x²-18=2(4x²-9)=2(2x-3)(2x+3)
x²+14x+49=x²+2(x)(7)+7²=(x+7)²
4x²-12x+9=(2x)²-2(2x)(3)+3²=(2x-3)²
2+16x+32x²=32x²+16x+2=2(16x²+8x+1)=2(4x+1)²
-9x²+30x-25 =9x²-30x+25 =(3x)²-2(3x)(5)+5²=(3x-5) ²

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

25k^2-36
= (5k)^2 - 6^2
= (5k+6) (5k-6)

3-27y^2
= 3 (1-9y^2)
= 3 [1 - (3y)^2]
= 3 (1+3y) (1-3y)

8x^2-18
= 2(4x^2 - 9)
= 2 [ (2x)^2 - 3^2}
= 2 (2x+3) (2x-3)

x^2+14x+49
= x^2 + 2*7*x + 7^2
= (x+7)^2

4x^2-12x+9
= (2x)^2 - 2*3*(2x) + 3^2
= (2x - 3)^2

2+16x+32x^2
= 2 (1+8x+16x^2)
= 2 [ 1+2*4x+(4x)^2 ]
= 2 (1+4x)^2

-9x^2+30x-25
= - (9x^2 - 30x + 25)
= - [ (3x)^2 - 2(3x)(5) + 5^2 ]
= - (3x-5)^2


2010-11-04 18:04:40 補充：
謝謝,,,,
我係girl....
nevermind