Question

giúp mik nha

a)(x-1)^3=27

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

c)(2x-1)^2+(x+3)^2-5(x+7)(x-7)=0

Answer 1

a, \(\left(x-1\right)^3=3^3\Rightarrow x-1=3\Leftrightarrow x=4\)

b, \(\left(x-3\right)^2-4=0\Leftrightarrow\left(x-5\right)\left(x-1\right)=0\Leftrightarrow x=1;x=5\)

c, \(4x^2-4x+1+x^2+6x+9-5\left(x^2-49\right)=0\)

\(\Leftrightarrow2x+10+245=0\Leftrightarrow2x=-255\Leftrightarrow x=-\dfrac{255}{2}\)

Answer 2

\(a,\left(x-1\right)^3=3^3\\ x-1=3\\ x=4\\ b,\left(x-3\right)^2=4\\ TH1\left(x-3\right)^2=2^2\\ x-3=2\\ x=5\\ TH2\left(x-3\right)^2=\left(-2\right)^2\\ x-3=-2\\ x=1\\ c,4x^2-4x+1+x^2+6x+9-5\left(x^2-49\right)=0\\ 5x^2+2x+10-5x^2+245=0\\ 2x+255=0\\ 2x=-255\\ x=-\dfrac{255}{2}\)