In a different plan for area codes, the first digit could be any number from 1 through 7, the second digit was either 4, 5, 6, or 7, and the third digit could be any number except 2. With this plan, how many different area codes are possible?

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204

the answer to your question is minor arc.

answer: c

step-by-step explanation