Question

Tìm x biết

a) (x-3)^2 -4=0

b) ( 2x+3)^2 - (2x+1)(2x-1) =22

c) (4x+3)(4x-3) -(4x-5)^2 =16

d) x^3 -9x^2 +27x-27 =-8

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

Answer 1

b) ( 2x+3)^2 - (2x+1)(2x-1) =22

=> 4x²+12x+9-4x²+1=22

=> 12x=12

=>x=1

c) (4x+3)(4x-3) -(4x-5)^2 =16

=>16x²-9-16x²+40x-25=16

=>40x=50

=>x=4/5

Answer 2

a)\(\left(x-13\right)^2-4=0\\\left(x-13\right)^2=4\\ \left(x-13\right)^2=2^2\\ \Rightarrow\left\{{}\begin{matrix}x-13=2\\x-13=-2\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}15\\-11\end{matrix}\right.\)

vậy...

Answer 3

d) x^3 -9x^2 +27x-27 =-8

=>(x-3)³=-8

=>x-3=-2

=>x=1

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

=>x³+3x²+3x+1-x³-3x²=2

=>3x=1

=>x=1/3