WBJEE · Maths · Basic of Mathematics
The number of solutions of the equation \(\log _{2}\left(x^{2}+2 x-1\right)=1\) is
- A 0
- B 1
- C 2
- D 3
Answer & Solution
Correct Answer
(C) 2
Step-by-step Solution
Detailed explanation
Given \(\log _{2}\left(x^{2}+2 x-1\right)=1\) \(\Rightarrow \quad \log _{2}\left(x^{2}+2 x-1\right)=\log _{2} 2\) \(\Rightarrow\) \(x^{2}+2 x-1=2\) \(\Rightarrow \quad x^{2}+2 x-3=0\) \(\Rightarrow \quad x^{2}+3 x-x-3=0\) \(\Rightarrow \quad x(x+3)-1(x+3)=0\) \(=(x+3)(x-1)=0\)…
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