Which trinomials are perfect square trinomials?Select each correct answer.a2+26a+169a2+4a+16a2+14a+49a2+15a+75Factor completely.4p² + 36p + 81Express the answer in the form (ap+b)2 .Enter your answer in the box.Factor.81a36−64b16(9a6−8b4)(9a6+8b4)(9a18−8b8)(9a18+8b8)(9a6−8b4)2(9a18−8b8)2Which expressions are differences of squares?Select each correct answer.x2−169h2−20t2−4a2+1

1. the perfect squares in this case are
a²+26a+169 = (a+13)²
a²+14a+49 = (a+7)²

2. factorising 
4p²+36p+81
 product = 324
      sum = 36
numbers are 18 and 18
Thus , 4p²+18p+18p+81
          2p(2p+9) +9p(2p+9)
thus, (2p+9p)(2p+9p)

3. Factor 81a36-64b16
this is the difference between two squares, such that;
a²-b² = (a+b)(a-b)
therefore, 81a36 -64b16 will be;
(9a18-8b8)(9a18+8b8)

4.  The differences between two squares is such that;
a²-b² = (a+b)(a-b)
therefore in this case, the difference between two squares will be;
x²-169 = (a-13)(a+13), and
t²-4     = (t-4)(t+4)