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(4x2)(10x+4)(5x+7)(2x+1)+17=0(4x−2)(10x+4)(5x+7)(2x+1)+17=0

(4x2)(5x+7)(10x+4)(2x+1)+17=0⇔(4x−2)(5x+7)(10x+4)(2x+1)+17=0

(20x2+18x14)(20x2+18x+4)+17=0⇔(20x2+18x−14)(20x2+18x+4)+17=0

Đặt t= 20x2+18x+4(t0)20x2+18x+4(t≥0) ta có:

(t-18).t +17=0

t218t+17=0⇔t2−18t+17=0

(t17)(t1)=0⇔(t−17)(t−1)=0

[t=17(tm)t=1(tm)⇔[t=17(tm)t=1(tm) [20x2+18x+4=1720x2+18x+4=1[20x2+18x13=020x2+18+3=0⇔[20x2+18x+4=1720x2+18x+4=1⇔[20x2+18x−13=020x2+18+3=0

[(20x+9341)(20x+9+341)=0(20x+921)(20x+9+21)=0⇔[(20x+9−341)(20x+9+341)=0(20x+9−21)(20x+9+21)=0

x=9+34120x=934120x=9+2120x=92120

6 tháng 6 2019

\(a,\)\(\left(4x-2\right)\left(10x+4\right)\left(5x+7\right)\left(2x+1\right)+17\)

\(=\left(4x-2\right)\left(5x+7\right)\left(10x+4\right)\left(2x+1\right)+17\)

\(=\left(20x^2+18x-5\right)\left(20x^2+18x+4\right)+17\)

Đặt ....

6 tháng 6 2019

\(a,\)\(x^3-13x-12\)

\(=x^3-x-12x-12\)

\(=x\left(x^2-1\right)-12\left(x+1\right)\)

\(=x\left(x-1\right)\left(x+1\right)-12\left(x+1\right)\)

\(=\left(x+1\right)\left(x^2-x-12\right)\)

\(=\left(x+1\right)\left(x^2-4x+3x-12\right)\)

\(=\left(x+1\right)\left[x\left(x-4\right)+3\left(x+4\right)\right]\)

\(=\left(x+1\right)\left(x-4\right)\left(x+3\right)\)

6 tháng 6 2019

a) \(x^3-13x-12\)

\(=x^3+x^2-x^2-x-12x-12\)

\(=x^2\left(x+1\right)-x\left(x+1\right)-12\left(x+1\right)\)

\(=\left(x+1\right)\left(x^2-x-12\right)\)

\(=\left(x+1\right)\left(x^2-4x+3x-12\right)\)

\(=\left(x+1\right)\left[x\left(x-4\right)+3\left(x-4\right)\right]\)

\(=\left(x+1\right)\left(x-4\right)\left(x+3\right)\)

b) \(2x^4+3x^3-9x^2-3x+2\)câu này hình như sai đề rồi, bạn xem lại nhen

c) \(x^4-3x^3-6x^2+3x+1\)câu này cx thế, bạn xem lại nha

a: x^3-7x-6

=x^3-x-6x-6

=x(x-1)(x+1)-6(x+1)

=(x+1)(x^2-x-6)

=(x-3)(x+2)(x+1)

b: =2x^3+x^2-2x^2-x+6x+3

=x^2(2x+1)-x(2x+1)+3(2x+1)

=(2x+1)(x^2-x+3)

c: =2x^3-3x^2-2x^2+3x+2x-3

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

=(2x-3)(x^2-x+1)

d: =2x^3+x^2+2x^2+x+2x+1

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

e: =3x^3+x^2-3x^2-x+6x+2

=(3x+1)(x^2-x+2)

f: =27x^3-9x^2-18x^2+6x+12x-4

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

29 tháng 8 2023

a) \(x^3-7x-6\)

\(=x^3-x-6x-6\)

\(=\left(x^3-x\right)-\left(6x+6\right)\)

\(=x\left(x^2-1\right)-6\left(x+1\right)\)

\(=x\left(x+1\right)\left(x-1\right)-6\left(x+1\right)\)

\(=\left(x+1\right)\left(x^2-x-6\right)\)

b) \(2x^3-x^2+5x+3\)

\(=2x^3+x^2-2x^2-x+6x+3\)

\(=\left(2x^3+x^2\right)-\left(2x^2+x\right)+\left(6x+3\right)\)

\(=x^2\left(2x+1\right)-x\left(2x+1\right)+3\left(2x+1\right)\)

\(=\left(x^2-x+3\right)\left(2x+1\right)\)

c) \(2x^3-5x^2+5x+1\)

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

\(=\left(2x^3-3x^2\right)-\left(2x^2-3x\right)+\left(2x-3\right)\)

\(=x^2\left(2x-3\right)-x\left(2x-3\right)+\left(2x-3\right)\)

\(=\left(x^2-x+1\right)\left(2x-3\right)\)

d) \(2x^3+3x^2+3x+1\)

\(=2x^3+x^2+2x^2+x+2x+1\)

\(=\left(2x^3+x^2\right)+\left(2x^2+x\right)+\left(2x+1\right)\)

\(=x^2\left(2x+1\right)+x\left(2x+1\right)+\left(2x+1\right)\)

\(=\left(2x+1\right)\left(x^2+x+1\right)\)

e) \(3x^3-2x^2+5x+2\)

\(=3x^3+x^2-3x^2-x+6x+2\)

\(=\left(3x^3+x^2\right)-\left(3x^2+x\right)+\left(6x+2\right)\)

\(=x^2\left(3x+1\right)-x\left(3x+1\right)+2\left(3x+1\right)\)

\(=\left(3x-1\right)\left(x^2-x+2\right)\)

f) \(27x^3-27x^2+18x-4\)

\(=27x^3-9x^2-18x^2+6x+12x-4\)

\(=\left(27x^3-9x^2\right)-\left(18x^2-6x\right)+\left(12x-4\right)\)

\(=9x^2\left(3x-1\right)-6x\left(3x-1\right)+4\left(3x-1\right)\)

\(=\left(3x-1\right)\left(9x^2-6x+4\right)\)

10 tháng 9 2016

Dài 166

b) 2x2+3x-27=2x2-6x+9x-27=2x(x-3)+9(x-3)=(x-3)(2x+9)

8 tháng 7 2015

b, x6-x4+2x3+2x3+2x2

=x2(x4-x2+4x+2)

c, ...=x(a2-2ab+b2)+y(a2-2ab+b2)

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

d, ...=xm+1.x3+xm+1-x-1

=xm+1(x3+1)-(x+1)

=xm+1(x+1)(x2-x+1)-(x+1)

=(x+1)(xm+3-xm+2+xm+1)