## College Algebra (11th Edition)

81$y^{4}$ - 450$y^{2}$ + 625
1. You are going to use the formula (a-b)(a+b)= $a^{2}$ - $b^{2}$ where a = 3y and b = 5 to multiply the first two binomial factors. Working:- (9$y^{2}$- 25)(9$y^{2}$- 25) 2. Then use the formula (a - b)$^{2}$ = $a^{2}$ - 2ab + $b^{2}$; where a = $9y^{2}$ and b = 25 to multiply the binomial. Working:- ($9y^{2}$)$^{2}$ - 2($9y^{2}$)(25) + $25^{2}$ Therefore the answer is 81$y^{4}$ - 450$y^{2}$ + 625