The formula for the area of a circle is A=πr^2.
If the area of a circle is represented by A=21π, what is the radius of the circle?
Round your answer to the nearest tenth.

Look at arnold's attempt to solve the equation for b: 3b = 12 b = 3 · 12 b = 36 describe the mistake that arnold made.

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

Carl is hanging pictures in his home. there is a space on a wall that has a width of 4 feet. carl has pictures with different widths. which picture width would fit in the space on the wall? a. 46 inches b. 60 inches c. 50 inches d. 54 inches