# Let F : [0, ∞) → R and G : R → R Be Defined by F ( X ) = √ X and G(X) = X. Find F + G, F − G, Fg and F G . - Mathematics

Let f : [0, ∞) → R and g : R → R be defined by $f\left( x \right) = \sqrt{x}$ and g(x) = x. Find f + gf − gfg and $\frac{f}{g}$ .

#### Solution

It is given that f : [0, ∞) → R and g : R → R such that

$f\left( x \right) = \sqrt{x}$  and g(x) = x .  $D\left( f + g \right) = [0, \infty ) \cap R = [0, \infty )$
So, f + g : [0, ∞) → R is given by
$\left( fg \right)\left( x \right) = f\left( x \right)g\left( x \right) = \sqrt{x} . x = x^\frac{3}{2}$
$D\left( \frac{f}{g} \right) = \left[ D\left( f \right) \cap D\left( g \right) - \left\{ x: g\left( x \right) = 0 \right\} \right] = \left( 0, \infty \right)$
So,
$\frac{f}{g}: \left( 0, \infty \right) \to R$  is given by
$\left( \frac{f}{g} \right)\left( x \right) = \frac{f\left( x \right)}{g\left( x \right)} = \frac{\sqrt{x}}{x} = \frac{1}{\sqrt{x}}$
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#### APPEARS IN

RD Sharma Class 11 Mathematics Textbook
Chapter 3 Functions
Exercise 3.4 | Q 9 | Page 38