The cost and revenue functions of a product are given by $C(x) = 20x + 4000$ and $R(x) = 60x + 2000$ respectively,where $x$ is the number of items produced and sold. The value of $x$ to earn profit is

When $R$ is the set of all real numbers,$\{x \in R: \frac{\sqrt{12-x-x^2}}{x+10} \leq \frac{\sqrt{12-x-x^2}}{2x+9}\} = $

The marks obtained by a student of Class $XI$ in first and second terminal examination are $62$ and $48$,respectively. Find the minimum marks he should get in the annual examination to have an average of at least $60$ marks.

The water acidity in a pool is considered normal when the average pH reading of three daily measurements is between $8.2$ and $8.5$. If the first two pH readings are $8.48$ and $8.35$,then find the range of $pH$ value for the third reading that will result in the acidity level being normal.

If the set of all solutions of $|x^2 + x - 9| = |x| + |x^2 - 9|$ is $[\alpha, \beta] \cup [\gamma, \infty)$,then $(\alpha^2 + \beta^2 + \gamma^2)$ is equal to:

The set of real values of $x$ for which the inequality $|x-1|+|x+1| < 4$ holds true is