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Toán Lớp 8: x(x-2)^3-(2-x)^2 4x^3-2x-y^2-y x^3-5x^2-14x (x+2)(x+3)(x+4)(x+5)-24

Home/ Toán Lớp 8: x(x-2)^3-(2-x)^2 4x^3-2x-y^2-y x^3-5x^2-14x (x+2)(x+3)(x+4)(x+5)-24

Toán Lớp 8: x(x-2)^3-(2-x)^2 4x^3-2x-y^2-y x^3-5x^2-14x (x+2)(x+3)(x+4)(x+5)-24

Bảo Châu Tháng Chín 18, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: x(x-2)^3-(2-x)^2
4x^3-2x-y^2-y
x^3-5x^2-14x
(x+2)(x+3)(x+4)(x+5)-24

Comments ( 1 )

tuyen98
18 Tháng Chín, 2022 at 11:21 chiều

Reply

Giải đáp:

a/ x(x-2)^3-(2-x)^2

= x(x-2)^3-(x-2)^2

= (x-2)^2[x(x-2)-1]

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

b/ 4x^2-2x-y^2-y

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

= (2x-y)(2x+y)-(2x+y)

= (2x+y)(2x-y-1)

c/ x^3-5x^2-14x

= (x^2+2x^2)-(7x^2+14x)

= x^2(x+2)-7x(x+2)

= x(x+2)(x-7)

d/ (x+2)(x+3)(x+4)(x+5)-24

= [(x+2)(x+5)][(x+3)(x+4)]-24

= (x^2+5x+2x+10)(x^2+4x+3x+12)-24

= (x^2+7x+10)(x^2+7x+12)-24

+Đặt x^2+7x+11=t ta được:

(t-1)(t+1)-24

= t^2-1-24

= t^2-25

= (t-5)(t+5)

⇔ (x^2+7x+11-5)(x^2+7x+11+5)

= (x^2+7x+6)(x^2+7x+16)

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