Đáp án:
Giải thích các bước giải:
a) (3x-2)(x+6)(x^2+5)=0
{3x-2=0 {x=2/3
->{x+6=0 -> {x=-6
{x^2+5=0 {x=- căn5
b) (2x+5)^2=(3x-1)^2
-> (2x+5)^2 - (3x-1)^2 =0
-> [(2x+5) + (3x-1)] [(2x+5) - (3x-1)]=0
-> ( 2x+5+3x-1 ) (2x+5-3x+1)=0
-> (5x+4)(-x+6)=0
-> { 5x+4=0 -> x= -4/5
{ -x+6 =0 x= 6
c) 4x^2(x-1)-x+1=0
->4x^2(x-1)-(x-1)=0
->(x-1)(4x^2-1)=0
->{ x-1=0 ->x=1
{ 4x^2-1=0 x=1/2
d) 9(2x+1)=4(x-5)^2
-> 18x + 9= 4*(x^2 - 10x +25 )
-> 18x + 9 = 4x^2 - 40x + 100
-> 18x - 4x^2 + 40x = 100-9
-> 58x - 4x^2 = 91
-> 58x - 4x^2 - 91 =0
-> 2x ( 29 - 2x ) -91=0
-> {2x =0 -> x=0
{29-2x=0 x=29/2
e) x^3-4x^2-12x+27=0
->(x^3+27)-(4x^2 +12x)=0
->(x+3)(x^2-3x+9) - 4x(x +3)=0
-> (x+3)(x^2-3x+9 - 4x )=0
-> (x+3)(x^2 - 7x+9 )=0
->{x+3=0 ->x=-3
{x^2 - 7x+9 =0 x={7+can13/2
{7-can13/2
f) x^3+3x^2-6x-8=0
->(x^3-8)+(3x^2-6x)=0
->(x-2)(x^2+2x+4)+3x(x-2)=0
-> (x-2)(x^2+2x+4+3x)=0
->{x-2=0 ->x=2 ->x=2
{x^2+2x+4+3x=0 x= x^2+5x+4 x={-1
{-4
