Question

初中 因式分解!!

①(x^2-5)^2－16x^2
②4yx^3+4(xy)^2+xy^3
③x^2-10x+24

先化简再求值:[(x+2y)(x-2y)－(x+4y)^2]÷4y,其中x=5,y=2

Answer 1

①原式=（x^2-5-4X）（x^2-5+4X）
=（脊扰x-5）（族野明x+1）（x+5）（x-1）
②原兆告式=xy[4x^2+4(xy)^2+y^2]
=xy(2x+y)^2
③原式=(x-4)(x-6)

原式等于（x^2-4y^2-x^2-8xy+16y^2）÷4y
=(12y^2-8xy)÷4y
=3y-2x
代入得-4

Answer 2

①(x^2-5)^2－16x^2
=(x^2-5-4x)(x^2-5+4x)
=(x-5)(x+1)(x-1)(x+5)

②4yx^3+4(xy)^2+xy^3
=xy(4x^2+4xy+y^2)
=xy(2x+y)^2

③x^2-10x+24
=(x-4)(x-6)

先化歼源衫简再氏腔求值:[(x+2y)(x-2y)－(x+4y)^2]÷4y,其中x=5,y=2
[(x+2y)(x-2y)－裂拦(x+4y)^2]÷4y
=[x^2-4y^2-x^2-16y^2-8xy]÷4y
=(-12y^2-8xy)/(4y)
=-3y-2x
=-3*2-2*5
=-16

Answer 3

1.（X+1）*（X-1)*(X+5)*(X-5)