MCQ
If $f(x) = 3x - 4,$ then $f^{-1} =$
- ✓$\frac{\text{y +4}}{3}$
- B$\frac{\text{y - 4}}{3}$
- C$\frac{\text{y - 3}}{4}$
- D$\frac{\text{y + 3}}{4}$
✓
Answer
Correct option: A.
$\frac{\text{y +4}}{3}$
Solution: (A) $\frac{\text{y +4}}{3}$
$f(x) = 3x - 4$ (Given) Say, $y = 3x - 4 ⇒ 3x = y + 4$
$\Rightarrow\text{x}=\frac{\text{(y+4)}}{3}$
$ ∴\text{f}^1\text{(x)}=\text{x}=\frac{\text{y+4}}{3}$
$f(x) = 3x - 4$ (Given) Say, $y = 3x - 4 ⇒ 3x = y + 4$
$\Rightarrow\text{x}=\frac{\text{(y+4)}}{3}$
$ ∴\text{f}^1\text{(x)}=\text{x}=\frac{\text{y+4}}{3}$
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