2 câu trả lời
Đáp án:
√(x + 3) - √(x - 4) = 1 (1)
x>=4
<=>(√(x + 3) -√(x - 4))√(x + 3) +√(x - 4)) = √(x + 3) +√(x - 4)
<=>(x+3)-(x-4) =√(x + 3) +√(x - 4)
<=>√(x + 3) +√(x - 4)=7(2)
(1)+(2)<=>2√(x + 3)=8
<=>x+3 =16
x=13 (n)
Đáp án:
√(x + 3) - √(x - 4) = 1 (1)
x>=4
<=>(√(x + 3) -√(x - 4))√(x + 3) +√(x - 4)) = √(x + 3) +√(x - 4)
<=>(x+3)-(x-4) =√(x + 3) +√(x - 4)
<=>√(x + 3) +√(x - 4)=7(2)
(1)+(2)<=>2√(x + 3)=8
<=>x+3 =16
x=13 (n)