Question

Giúp mình bài 2 với

Answer 1

Bài 2: 

a: =>(7-4x)(7+4x)=0

=>x=7/4 hoặc x=-7/4

b: \(\Leftrightarrow\left(2x-x^2-1\right)\left(2x+x^2+1\right)=0\)

=>(x-1)(x+1)=0

=>x=1 hoặc x=-1

c: \(\Leftrightarrow\left(x-2\right)\left(x-3\right)\left(x+3\right)=0\)

hay \(x\in\left\{2;3;-3\right\}\)

 

Answer 2

a, \(16x^2+49=0\left(voli\right)\)

b, \(x^3-2x^2-9x+18=0\Leftrightarrow x^2\left(x-2\right)-9\left(x-2\right)=0\)

\(\Leftrightarrow\left(x-2\right)\left(x+3\right)\left(x-3\right)=0\Leftrightarrow x=2;x=3;x=-3\)

c, \(\left(x-1\right)^3-\left(x-1\right)^2=0\Leftrightarrow\left(x-1\right)^2\left[\left(x-1\right)-1\right]=0\Leftrightarrow x=1;x=2\)

d, \(\left(2x-x^2-1\right)\left(2x+x^2+1\right)=0\Leftrightarrow\left(x-1\right)^2\left(x+1\right)^2=0\Leftrightarrow x=1;x=-1\)

e, \(\left(x-2\right)^3=0\Leftrightarrow x=2\)

f, \(\left(x-1\right)\left(x^2+x+1\right)+x\left(1-x\right)=0\Leftrightarrow\left(x-1\right)\left(x^2+1>0\right)=0\Leftrightarrow x=1\)