We have 26 - 18 = 8; 34 - 26 = 8; 42 - 34 = 8; (an arithmetic progression)
We use the formula an = a1 + (n-1)x8 (the explicit formula)
So, an = 18 + (n-1)x8 ;
Then, an = 8n + 10;
Finally, a52 = 8x52 + 10 = 426 (the 52nd term);
For part a x=0 because anything to the power of 0 is 1
For part b any number could be x, because 7^0 is one and 1 to the power of anything will be 1
Hope this helps!