Question

Tìm x:

a)x(2x-4)-(x-2)(2x+3)

b)x(3x+2)+(x+1)^2-(2x-5)(2x+5)=-12

c)(x-1)(x^2+x+1)-x(x-3)^2=6x^2

d)x^2-x=0

e)(x+2)(x-3)-x-2=0

f)3x^3-27x

Giup mik vs nha

Answer 1

câu a không có về phải=> k làm dc

Answer 2

b)x(3x+2)+(x+1)^2-(2x-5)(2x+5)=-12

<=> 3x^2 +2x +x^2+2x+1 - 4x^2 +25 +12=0

<=> 4x+38=0

=>4x= -38

=>x= -38/4= -19/2

Answer 3

d)x^2-x=0

<=>x(x-1)=0

=>x=0 hoặc x-1=0

=>x=0 hoặc x=1

Answer 4

e)(x+2)(x-3)-x-2=0

<=>x^2 +2x-3x-6-x-2=0

<=> x^2 -2x-8=0

<=> x^2 +2x -4x-8=0

<=> x(x+2) -4(x+2)=0

<=>(x+2) (x-4)=0

=> x+2=0 hoặc x-4=0

=>x=-2 hoặc x=4

Answer 5

f)3x^3-27x

ko có vế phải => k làm dc

Answer 6

c)(x-1)(x^2+x+1)-x(x-3)^2=6x^2

<=> x^3 +x^2 +x -x^2 -x -1 -x.(x^2-6x+9) - 6x^2=0

<=> x^3 +x^2 +x -x^2 -x-1 -x^3 +6x^2-9 -6x^2=0

<=>0x - 10=0

=> 0x= 10 (vô lí)

=> Pt vô nghiệm