Which polynomial is a perfect square trinomial? a. x^2 +5y + 25 b. x^2 +10y+25 c. x^2+5y+100 d. x^2+10y-25

The definition of a perfect square trinomial:
When a square of a number (3*3=9) can also add up to another number in the trinomial (3+3=6)

In my example here the equation, in order to be a perfect square trinomial, would be: X^2+6y+9

Now to look at the problem. We can instantly single out C because 10*10 is 100 but 10+10 is not five.
If we look at A we can find the root of 25 (5) but 5+5 is 10 not five. So A is incorrect
Using our previous calculation we know that 5 is our magic number. Leaving us with B and D. If we look at D we can conclude that -5*5 would be -25 but -5+5 is zero. So, it is not D
Using power of elimination we can easily conclude that B is the correct answer. If you wish to check: (5+5=10) (5*5=25)

B

Hope this helped!