Question

Let $f(x)=x^2-3x+4$, the value of x, which satisfies $f(1)+f(x)=f(1)f(x)$, is

• A. $1$
• B. $2$
• C. $1$ or $2$
• D. $1$ and $0$

Answer 1

Answer: (C)

$f(x)=x^2-3x+4$
$\therefore f(1)=2$ and x satisfies the condition
$f(1)+f(x)=f(1)f(x)$
$\therefore 2+x^2-3x+4=2(x^2-3x+4)$
$\Rightarrow x^2-3x+2=0$
$\Rightarrow x=1,x=2$