Find the area of the circle in simplest polynomial form. A = 3.14r2
2x+1

a: 6.28x2 + 3.14
b: 12.56x2 + 3.14
c: 6.28x2 + 3.14x + 3.14
d: 12.56x2 + 12.56x + 3.14

Question

Find the area of the circle in simplest polynomial form. A = 3.14r2
2x+1

 a: 6.28x2 + 3.14
 b: 12.56x2 + 3.14
 c: 6.28x2 + 3.14x + 3.14
 d: 12.56x2 + 12.56x + 3.14

anonymous · Answer

What one you think?

anonymous · Answer

A

nurali · Answer

A = 3.14r^2
since r = 2x+1

A = 3.14(2x+1)^2
Now all you have to do is simplify this expression.

A=3.14(2x+1)(2x+1)
A=3.14(4x^2 + 2x + 2x + 1)
A=3.14(4x^2 +4x+1)
A=12.56x^2 + 12.56x + 3.14

welshfella · Answer

Oh  yes - i didn't understand the question at first 
you didnt say that r = 2x + 1

anonymous · Answer

i don't know how to do that

welshfella · Answer

the answers  not A

welshfella · Answer

Nurali has worked it out for you

welshfella · Answer

you just say A = 3.14 r^2   
when r = 2x + 1

anonymous · Answer

is it B

anonymous · Answer

i really don't understand how to do this stuff

anonymous · Answer

hello?

welshfella · Answer

its basic algebra
you replace the r in 3.14 r^2 by 2x + 1
and simplify