Đáp án:
a, Căn 3x-5=3+căn x-2 ĐKXĐ: x >=2
<==> (căn 3x-5)^2=(3+căn x-2)^2
<==> 3x-5=9 + 6*căn x-2 + x-2
<==>3x-5=x+7 + 6*căn x-2
<==>2x-12=6*căn x-2
<==>2(x-6)=6*căn x-2
<==>x-6=3*căn x-2
<==>(x-6)^2=(3*căn x-2)^2
<==>x^2-12x+36=9(x-2)
<==>x^2-21x+54=0
<==>(x-18)(x-3)=0
<==>x=18 hoặc x=3 (TMĐKXĐ)
b,
Căn x+1=8-căn 3x+1 ĐKXĐ: x <=21
<==> (căn x+1)^2=(8-căn 3x+1)^2
<==> x+1=64- 16*căn 3x+1 + 3x+1
<==>x+1=3x+65 - 16*căn 3x+1
<==>16*căn 3x+1=2x-64
<==>16*căn 3x+1=2(x-32)
<==>8*căn 3x+1=(x-32)
<==>(8*căn 3x+1)^2=(x-32)^2
<==>64(3x-1)=x^2-64x+1024
<==>x^2-256x+1088=0
<==>x=108/25 hoặc x=251,935(TMĐKXĐ)