Step-by-step explanation:
8.
Let the number is x. A number minus 7 is (x-7). It is doubled to get 86. So,
[tex](x-7)^2=86\\\\x-7=\sqrt{86}\\\\x-7=\pm 9.27\\\\x-7=9.27\ and\ x-7=-9.27\\\\x=16.27\ or\ x=-2.27[/tex]
The number can be 16.27 or -2.27.
9.
The diameter of the cylindrical tank, d = 20 ft
Radius, r = 10 ft
It is filled with oil to a depth of h feet.
The volume of a cylindrical shaped object is given by :
[tex]V=\pi r^2 h[/tex]
Put the given values,
[tex]V=\pi (10)^2h\\\\V=3.14\times 100\times h\\\\V=314h\ ft^3[/tex]
So, the volume of the tank is equal to [tex]314h\ ft^3[/tex].
