Answer:
561
Step-by-step explanation:
an = dn - (a-d)
The difference is 3.
The first term is 12.
an = 3n - (12-3)
an = 3n - 9
Put n as 1, 2, 3, 4, 5 ....22.
3(1) - 9 = -6
3(2) - 9 = -3
3(3) - 9 = 0
3(4) - 9 = 3
3(5) - 9 = 6
...
3(22) - 9 = 57
Add the first 22 terms.
-6+-3+0+3+6+9+12+15+18+21+24+27+30+33+36+39+42+45+48+51+54+57
= 561
Answer. z = ± √10 = ± 3.1623
X+y+z=32
x=z-4
y=x+1
z=x+4
x+x+1+x+4=32
3x+5=32
3x=27
x=9
y=10
z=13
Hope this helps :)