The height of a cone is two times its base diameter. what is the volume of the cone in terms of its base radius r? a. v=(pi)(r²) b. v=(pi)(r³) c. v=(pi)(r³) d. v=(pi)(r²)

B

Step-by-step explanation:

Assume the radius is r so the diameter is 2r

Height=2*d=2(2r)=4r since the diameter is twice the radius

Volume of cone=1/3 * pi*r^2*h

                         = 1/3 * pi*r^2*(4r)

                         =4/3 *pi *r^3

So B

B

h=2d

r=d/2

so h in terms of r is;

h=4r

V=pi*r^2*h/3

V=pi*r^2*4r/3=pi*4r^3/3=4/3(pi)(r^3)

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18