If the 2nd and 5th terms of a
1 answer:
Answer:
45
Step-by-step explanation:
The n th term of a GP is
= a
where a is the first term and r the common ratio
Given a₂ = 6 and a₅ = 48, then
ar = 6 → (1)
a = 48 → (2)
Divide (2) by (1)
=
, that is
r³ = 8 ( take the cube root of both sides )
r = = 2
Substitute r = 2 into (1)
2a = 6 ( divide both sides by 2 )
a = 3
Thus
3, 6, 12, 24 ← are the first 4 terms
3 + 6 + 12 + 24 = 45 ← sum of first 4 terms
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Answer:
The volume of the tetrahedron is:
Step-by-step explanation:
The volume of the tetrahedron is given by the intersection of the planes x = 0, y = 0, z = 0 and the plane formed by the three points given.
The equation of the plane formed by the three points is:
Points: (2,0,0);(0,5,0);(0,0,4)
It can also be expressed as:
We have to calculate the triple integral, therefore we must define the domain:
The values of x are given by:
0≤x≤2
We will integrate the values of y between the y = 0 axis and the line formed when z = 0:
z=0 ⇒ 10x + 4y=2 ⇒
We will integrate the values of z between the plane z = 0 and the plane 10x + 4y+5z=20
10x + 4y+5z=20 ⇒
The volume of the tetrahedron is: