The expression for the cost of the ABC Book Club is 2x + 40. The expression for the cost of the Easy Book Club is 3x + 35. To find when the total charge for both book clubs is equal, the two expressions must equal each other. (x = the number of books read)
2x + 40 = 3x + 35
Subtract 35 from both sides.
2x + 5 = 3x
Subtract 2x from both sides.
5 = x
So, the total charge for each club is equal when 5 books are read.
Multiplying x^2 by 5 stretches the graph vertically by a factor of 5. Try graphing both x^2 and 5x^2 and see for yourself that this is correct.
To cover at least 170.5 sq.ft. the width must be at least 11 feet
W=170.5sq.ft / 15.5 ft = 11ft