If (f:\mathbb{R}\to\mathbb{R}) is defined by (f(x)=2x-5), which statement about (f) is correct?

Correct answer: One-one and onto

Step 1: (f(x)=2x-5) is linear with non-zero slope, so distinct inputs give distinct outputs. Step 2: For any (y\in\mathbb{R}), (x=\frac{y+5}{2}) is real, so every real output is attained. Step 3: In exams, remember that (ax+b) with (a\neq0) is both one-one and onto from (\mathbb{R}) to (\mathbb{R}).