The 15th term of arthimetic sequence is 43 and the common difference is 4 find the first term

Step-by-step explanation:

hello :

the nth term of an arithmetic sequence is :

An =An+(n-p)d   a common difference is : d  

let : n=15    and   p=1    d= 4     A15 =43

A15 = A1 + (15-1)(4)

43= A1 +56

A1= 43-56 = - 13

b). 4320 have a nice day

first, you divide the triangle in two, tô form a retangle triangle. after, using pythagoream theorem:

18^2 = 14^2 + (x/2)^2

(x^2/4) + 196 = 324

x^2/4 = 324 - 196

x^2/4 = 128

x^2 = 512

x = √512

x = √2^9

x = 16√2 cm

i hope i you.