Answer:
25 and 29
Step-by-step explanation:
let the two arithmetic mean be b and c respectively.
U(1)=21 and since it is the first term then, a=21
2nd term that is U(2)=b
3rd term that is U(3)=c
4th term that is U(4)=33
Now U(2)=(a+d) that is b
U(3)=(a+2d) that is c
U(4)=(a+3d) that is the 4th term
find d using the 4th term
a+3d=33
21+3d=33
3d=33-21
3d=12
d=12÷33
d=4
therefore
b= a+d ( second term)
b=21+4
b=25
then
c=a+2d ( 3rd term )
c=21+2×4
c=21+8
c=29
