А) The surface area of a sphere is a sq. cm. If its radius is doubled, by how much does
its surface area increase?

Step-by-step explanation:

surface area of sphere=a

4pir^2=a

r^2=a/4p

r=root(a/4pi)

if radius is doubled

r1=2root(a/4pi)

r1^2=4(a/4pi)

a/a1=(4pia/4pi)/(4pi 4a/4pi)=1/4

so a is increased by 4 times

4th option is correct xy=-10

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