Answer:
see explanation
Step-by-step explanation:
(a)
Expressing as a difference of squares
a² - b² = (a - b)(a + b), thus
x² - 720
= x² - (12[tex]\sqrt{5}[/tex] )²
= (x - 12[tex]\sqrt{5}[/tex] )(x + 12[tex]\sqrt{5}[/tex] )
(b)
15xy + 15 + 9y + 25x ← rearrange
= 15xy + 9y + 25x + 15 ( factor the first/second and third/fourth terms )
= 3y(5x + 3) + 5(5x + 3) ← factor out (5x + 3)
= (5x + 3)(3y + 5) ← in factored form
