Plug in 300 for C(x), to get:
300=

Then subtract to get: 0=

Then use the quadratic formula and plug everything in. Use a calculator to simplify.
You'll get two answers: 29.486 and -0.513.
Since you can't sell <em>"negative" </em>tacos, use the positive solution
Around 29-30 tacos.
Expand it
-(x+3)^2-1
-(x+3)(x+3)-1
-1(x^2+3x+3x+9)-1
-1(x^2+6x+9)-1
-x^2-9x-9-1
-x^2-9x-10
f(x)=-x^2-9x-10
Y=1.6x+2
that’s just what i got
Answer:
22 inch is the diameter because d =2r