Answer: 320ft^3
Step-by-step explanation:
Assuming the pyramid is just a normal rectangular pyramid and isn't made of stairs...
10x8x12/3 = 320 ft^3
9x^3-39x^2-38x+40=(3x-2)(3x+4)(x-5) by synthetic division
Thus roots are -4/3, 2/3, 5
7x-15=-2
Move -15 to the rigjt side,
7x=-2+15
7x=13
Divide both sides by 7,
7x/7=13/7
x=13/7
The triangles are similar by the SSS (side-side-side) similarity theorem because the sides of the two triangles are in proportion (5/15 = 3/9 = 4/12)
Hope this helps =)
Step-by-step explanation:
So what are you looking for with that equation?