#### Answer

$(8x-9)^{2}$

#### Work Step by Step

$64x^{2}$-144x+81
Using the rule of
$a^{2}$-2ab+$b^{2}$= $(a-b)^{2}$
*** Take the square root of 64 which is 8. Becuase 8 × 8= 64
*** Take the square root of 81 which is 9. Becuase 9 × 9= 81
In this case, the a= 8 and b= 9 as substituting these gives us the original polynomial
$a^{2}$-2ab+$b^{2}$
$(8x)^{2}$-2(8x)(9)+$9^{2}$
$64x^{2}$-144x+81
Thus:
$64x^{2}$-144x+81
= $(8x-9)^{2}$
= (8x-9)(8x-9)