Question

Hey guys I really need help. You don't have to give the answer I just really need an explanation as to how to find the roots with work, thank you so much.
Find the roots of f(n)=n^2-2n-15.
Tip: The ^2 means "to the power of" so n^2 is n to the power of 2.
Please help!

Answer 1

Answer:

Step-by-step explanation:

1. by making factors

consider ax²+bx+c=0

if a×c or ac>0 , then break b=d+e such that de=ac

if ac<0,then write b=d-e (e.g.,5-2=3)

such that de=ac

here n²-2n-15

1×-15=-15

-2=-(5-3)

5×-3=-15

n²-2n-15=n²-(5-3)n-15

=n²-5n+3n-15

=n(n-5)+3(n-5)

=(n-5)(n+3)

roots are n-5=0,n=5 and n+3=0,n=-3

2. by using formula

ax²+bx+c=0

$x=\frac{-b \pm \sqrt{b^2-4ac} }{2a} \\n^2-2n-15=0\\n=\frac{2 \pm\sqrt{(-2)^2-4*1*-15} }{2*1} \\=?$

Answer 2

Answer:

x=9 is the answer

Step-by-step explanation:

you do 2^2 then 2-2 you add those two answer together than subtract from 15