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4-2.Quadratic Equations and Inequations
easy
If $\sqrt {3{x^2} - 7x - 30} + \sqrt {2{x^2} - 7x - 5} = x + 5$,then $x$ is equal to
A
$2$
B
$3$
C
$6$
D
$5$
Solution
(c) $\sqrt {3{x^2} – 7x – 30} + \sqrt {2{x^2} – 7x – 5} = x + 5$
$\sqrt {3{x^2} – 7x – 30} = (x + 5) – \sqrt {2{x^2} – 7x – 5} $
on squaring, $\sqrt {2{x^2} – 7x – 5} = 5$
$2{x^2} – 7x – 30 = 0\,\, \Rightarrow \,\,x = 6$.
Standard 11
Mathematics