標題:

因式分解(數學)

發問:

1.16a^4-b^4 2.(x+y)^2+6z(x+y)+9z^2 3.(m-n)^2-8m(m-n)+16m^2 4.2ab-a^2-b^2 5.x^3+4x^2yz+4xy^2z 6.(x^2+4)^2-16x^2 13.(二分之一x + 三分之二y -四分之三z)^2 -(二分之一x-三分之二y-四分之三z)^2

最佳解答:

1.16a^4-b^4 = (2a)^4 - b^4 = [(2a)^2 - b^2][(2a)^2 + b^2] = (2a-b)(2a+b)(4a^2+b^2)2.(x+y)^2+6z(x+y)+9z^2 = (x+y+3z)(x+y+3z)3.(m-n)^2-8m(m-n)+16m^2 = (m-n-4m)(m-n-4m) = (3m+n)(3m+n)4.2ab-a^2-b^2 = -(a^2-2ab+b^2) = -(a-b)(a-b)5.x^3+4x^2yz+4xy^2z = x(x^2+4xyz+4y^2z) = x(x+2yz)(x+2yz)6.(x^2+4)^2-16x^2 = (x^2+4+4x)(x^2+4-4x) = (x+2)^2(x-2)^2 = (x^2-4)^213 (x/2 + 2y/3 -3z/4)^2 -(x/2-2y/3-3z/4)^2 = (x/2+2y/3-3z/4+x/2-2y/3-3z/4)(x/2+2y/3-3z/4-x/2+2y/3+3z/4) = (x-6z/4)(4y/3)

其他解答:

1. 16a^4-b^4 =(4a^2+b^2)(4a^2-b^2) =(2a-b)(2a+b)(4a^2+b^2) 2. (x+y)^2+6z(x+y)+9z^2 =[(x+y)+3z]^2 =(x+y+3z)^2 3. (m-n)^2-8m(m-n)+16m^2 =[(m-n)-4m]^2 =(3m-n)^2 4. 2ab-a^2-b^2 =-a^2+2ab-b^2 =-(a-2ab+b)^2 =-(a-b)^2 5. x^3+4x^2yz+4xy^2z =x(x^2+4xyz+4y^2z) =x(x+2yz)^2 6. (x^2+4)^2-16x^2 =[(x^2+4)-4x][(x^2+4)+4x] =(x^2-4x+4)(x^2+4x+4) =(x-2)^2(x+2)^2 13. (x/2 + 2/3y -3/4z)^2 -(x/2-2/3y-3/4z)^2 =[(x/2 + 2/3y -3/4z )-(x/2-2/3y-3/4z) ][(x/2 + 2/3y -3/4z)+(x/2-2/3y-3/4z) ] =(5x/2)(8y/3+11z/4) =(5x/2)[(32y+32z)/12]

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