Please help I will give out brainliest and 100 points

min. thickness of the book is 53.8mm

Step-by-step explanation:

400 pages, each page thickness = 0.13mm

front and back cover thickness = 0.9mm

total thickness of the book = front + 400 pages + back cover

total = 0.9 + (400 x 0.13) + 0.9

total = 0.9 + 52 + 0.9

total = 53.8 mm

$649.60

step-by-step explanation:

let's call the solutions x₁ = (5 - 2√7)/3 and x₂ = (5 + 2√7)/3

then the equation is (x-x₁)(x-x₂) = 0

if you fill that in you get a lot of numbers which you can recognize as ax²+bx+c=0.

step-by-step explanation:

you can see that a=1 (there is just an x²)

b = (-5 -2√7 + 2√7 - 5)/3 = -10/3

c = -2√7)/3 ) * (-5+2√7)/3) = -1/3

so your answer is 3x^2 – 10x – 1 = 0