Mathew invested $3000 into two accounts. One account paid 3% interest and the other paid 8% interest. He earned 4% interest on the total investment

Step-by-step explanation:

What is the question?

a. is correct

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