數學難題()

(x-3)^2-4x^2
=x^2-3^2-4x^2
=-3x^2-6
(^2=二次方)
希望幫到你啦^^

^=次方
(x-3)^2-4x^2
(x-3)(x-3)-4x^2
x^2-3x-3x+9-4x^2
-3x^2-6x+9

So,(x-3)2次方-4x2次方is -3x^2-6x+9


I hope I can help you!! Thank you!!

(x-3)^2 - (4x)^2
= x^2 - 6x + 9 - 16x^2
= -15x^2 - 6x + 9
= -3(5x^2 - 2x + 3)
= -3(5x+1)(x-1)

OR

use the equality of a^2 - b^2 = (a+b)(a-b)
(x-3)^2 - (4x)^2
= (x-3+4x)(x-3-4x)
= (5x+3)(-3x-3)
= (5x+3)(-3)(x-1)
= -3(5x+1)(x-1)

ans: -3(5x-3)(x+1)

下面我用*代表2次方:

(x-3)*-(4x)*
= x*-6x+9-16x*
= -15x*-6x+9
= -3(5x*+2x-3)
= -3(5x-3)(x+1)