Evaluate the expression c+20

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Write the equations in logarithmic form 10^3=1,000

To keep cylindrical tanks from tipping over, a designer is planning to enlarge the original area of the base by 50%. the new tank should have the same volume as the original. how should the designer change the height of the tank? a: make it 50% taller than the height of the original tank. b: make it 6623% taller than the height of the original tank c: make it 3313% shorter than the height of the original tank d: make it 50% shorter than the height of the original tank.