Let [x] denote the greatest integer less than or equal to x. Then, the values of x$\in$R satisfying the equation ${[{e^x}]^2} + [{e^x} + 1] - 3 = 0$ lie in the interval :
Solution
${[{e^x}]^2} + [{e^x} + 1] - 3 = 0$<br><br>$\Rightarrow {[{e^x}]^2} + [{e^x}] + 1 - 3 = 0$<br><br>Let $[{e^x}] = t$<br><br>$\Rightarrow {t^2} + t - 2 = 0$<br><br>$\Rightarrow t = - 2,1$<br><br>$[{e^x}] = - 2$ (Not possible)<br><br>or $[{e^x}] = 1$ $\therefore$ $1 \le {e^x} < 2$<br><br>$\Rightarrow \ln (1) \le x < \ln (2)$<br><br>$\Rightarrow 0 \le x < \ln (2)$<br><br>$\Rightarrow x \in [0,\ln 2)$
About this question
Subject: Mathematics · Chapter: Complex Numbers and Quadratic Equations · Topic: Complex Numbers and Argand Plane
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