Hey can u help me pls.

15 dots

Step-by-step explanation:

formula :: 1/2 x n ( n +1 )

fig 1 ; 1 /2 x 1 ( 1+1 ) = 1 dot

fig 2 :; 1/2 x 2 ( 2+1 ) = 3 dots

fig 5 :: 1/2 x 5 ( 5+1 ) = 15 dots

f(x) = - 2/3x + 5; f(5/2)

substitute 5/2 in for x:

f(5/2) = -2/3(5/2) + 5

simplify the right side:

f(5/2) = -5/3 + 5

f(5/2) = 10/3

answer:

f(5/2) = 10/3

i hope this you!

18

step-by-step explanation:

draw the shape and you will see that f and k are actually at adjacent vertices (points of the hexagon that are neighboring).   so find the distance between (1,2) and (4,2).   that is easy since (1,2) and (4,2) is just a vertical distance to count, which is 3.   it is a regular polygon which means all sides are congruent.   you have 6 sides (hexa) so multiply 6 by 3 to receive 18.