Choose one value of x that proves that the student's claim is not true.

option b i.e -2

y=2x+5 (given)

Now, when x = -2

y=2(-2)+5

= -4+5

=1

The student claims that when x is (-) ve then y is also (-) ve, which is not true when x=-2

because here x is (-) ve and y is (+) ve

256π units²   (answer b)

step-by-step explanation:

the formula for the surface area of a sphere of radius r

is             a = 4πr²

and so, if r = 8 units, then the surface area is:

a = 4π(8 units)² = 256π units²   (answer b)

2.83941151 would be the answer you're looking for! : )