Absolutely ! If you have two vectors with equal magnitudes and opposite
directions, then one of them is the negative of the other. Their correct
vector sum is zero, and that's exactly the magnitude of the resultant vector.
(Think of fifty football players pulling on each end of the rope in a tug-of-war.
Their forces are equal in magnitude but opposite in sign, and the flag that
hangs from the middle of the rope goes nowhere, because the resultant
force on it is zero.)
This gross, messy explanation is completely applicable when you're totaling up
the x-components or the y-components.
Answer:
magnification will be -0.025
Explanation:
We have given the radius of curvature = 12 cm
And object distance = 3 m
So focal length 
Now for mirror we know that 
So 
v = 0.750 m
Now magnification of the mirror is 
Avogadro's mole is a number, like 6.023 *10^23
your question is the equivalent of asking if 100 feathers or 100 bricks weigh more
the mole of bricks would weigh more
