A student solved for the radius of a circle with a circumference of 12π

Step 1: C = 2 pi r. Step 2: 12 pi = 2 pi r. Step 3: StartFraction 12 pi over 2 pi EndFraction = StartFraction 2 pi r over 2 pi EndFraction. Step 4: 6 = pi r. Step 5: StartFraction 6 over pi EndFraction = StartFraction pi r over pi EndFraction. Step 6: Solving for r, the length of the radius is StartFraction 6 over pi EndFraction centimeters. in which stept did he made the error

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.

How do you determine if an ordered pair is a solution to a given equation?

The diagram represents the polynomial 4x2 + 23x – 72. what is the factored form of 4x2 + 23x – 72? (4x + 8)(x – 9) (4x – 8)(x + 9) (4x + 9)(x – 8) (4x – 9)(x + 8)