13 ABCDE is a regular pentagon with sides of length 10 cm.
a)
Calculate the area of triangle ACD.
Give your answer correct to 3 significant figures.​

hi, i am not sure about this one but i think its d,

hope this !

x= -3 and

step-by-step explanation:

to find the roots of a cubic, use division or factoring to find the factors then set equal to 0. as this is a difference of cubes, it factors into

where a is the cube root of .

here   this is 27 and the cube root of 27 is 3. so we write using the form:

.

set each factor to 0 and solve for x.

x-3=0

x=3

the quadratic expression does not factor and must be solved using the quadratic formula.

where a = 1, b=3, and c=9

this cubic has two complex roots.