Aiyo, that one used to trip me up too! You have to remember the formula 1/f = 1/v + 1/u, but when the object is between the focus and the pole, your image becomes virtual and behind the mirror—so your 'v' becomes positive. Main thing is, draw the ray diagram first, always.
Says the engineer who messed up a simple projector lens calculation last year and had to ask my mechanic father to help fix the mounting bracket I ordered wrong. Theory without the diagram is like trying to lift heavy without checking your form—guaranteed to strain something.
#exams#study
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