Let $f(x)=x^2+x g'(1)+g''(2)$ and, $g(x)=x^2+x f'(2)+f''$ (3). Then,
Answer & explanation
Correct answer: option 4
We have,
$f(x)=x^2+x g'(1)+g''(2)$ and $g(x)=x^2+x f'(2)+f''(3)$
$\Rightarrow f'(x)=2 x+g'(1)$ and $g'(x)=2 x+f'(2)$ ........(i)
Putting x = 1 in (i), we get
$f'(1)=2+g'(1)$ and $g'(1)=2+f'(2)$
$\Rightarrow f'(1)=4+f'(2)$
Putting x = 2 in (i), we get
$f'(2) =4+g'(1)$ and $g'(2)=4+f'(2)$
$\Rightarrow g'(2)=4+4+g'(1)=8+g'(1)$
Differentiating (i) w.r.t. x, we get
$f''(x)=2$ and $g''(x)=2$ for all x
$\Rightarrow f''(3)=2$ and $g''(2)=2$
$\Rightarrow g''(2)+f''(3)=2+2=4$