Ireally need with my alegbra

the topic is number sequences.

1. a grocer stacks cans in a sqaure pyramid with 10 layers. the number of cans in each layer makes a pyramidal sequence. how many cans are in the pyramid?
*side note i'm not sure if i use the recursive formula or the explicit formula for the pyramidal sequence. it would mean alot of someone can explain this step by step*

2.the 14th term in the fibanacci sequence is 233. the 15th term is 377. what is the 16th term?

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.

Evaluate the discriminant of each equation. tell how many solutions each equation has and whether the solutions are real or imaginary. x^2 - 4x - 5 = 0