Which of the following cannot be made from a cross section of a cylinder? A. Parallelogram
B. Ellipse
C. Circle
D. Square

Step-by-step explanation:

Any cross-section of the sphere is a circle. The vertical cross-section of a cone is a triangle, and the horizontal cross-section is a circle. The vertical cross-section of a cylinder is a rectangle, and the horizontal cross-section is a circle.

b

Step-by-step explanation:

i don't know if is right but just trying to help

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for

the answer is d

step-by-step explanation: