3x^2-12x-21=0 solve by completing the square

Are carpet coast $15 per square metre. the total delivery charge is $21 peter buys n squared metres of carpet what is the expression which represents the total cost in $

What is the solution set of the quadratic inequality x^2-5< or equal to 0

Ametal rod needs to be 9 feet and 5.5 inches in length. the sections of the poles being used are each 1 foot and 10.5 inches long. how many 1ft 10.5in sections would be needed to complete the 9ft 5.5in metal rod? and how many inches of material will be left?