b = sqrt of a

Means b could be 1,2,3,4,5,6,7,8,9,10 etc..

A be 1,4,9,16,25,36,49,64,81,100 etc..

30 = 25 + 5

72 = 64 + 8

Other options don’t work.

a, band c are positive integers. If b equals the square root of a, and if c equals the sum of a and b, which of the following could be the value of c?

Indicate all such values.

A. 21
B. 30
C. 45
D. 72
E. 100
F. 331

Stem a,b ,c = +ve
If b= (a)^(1/2)
c= a+b. b^2 =a

c= b^2+ b =b(b+1)
.: c= b(b+1) or (even)(odd) or (odd)(even)
.: c must be even and could the above
So A,C and F is out !!
Now B,D,and E ,let’s check even•odd
B (30= 3•10) (Even•odd ) yes!
D (72= 3•24) (Even•odd) yes!
E (100=5•20) (Even•odd) yes but E could also be (even)^2 (10•10)
Which is not a feature of C at all so and could never be so Out!

So B and D
Open to corrections though

Posted from my mobile device

Can't 72 also be 2*36 in which case it would also not fulfill the requirement of C
I also had a confusion, does C only have to fulfill being even*odd or odd* even, doesnt it also have to be consecutive numbers since c=b(b+1)

I solved by plugging in numbers and got the right answer as well:

If a = 4 B = 2 C = 6, see chart below:
A B C
4 2 6
9 3 12
16 4 20
25 5 30
36 6 42
64 8 72

Only B and D are correct.