The coordinates of the endpoints of QR are Q (8, 2) and R (5, 7).Which measurement is closest to the length of QR in units? A 5.8 units B 5 units C 4 units D 3.9 units

Correct answer is A. 5.8 units

Step-by-step explanation:

got this correct on my test :)

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