Question

HELP PLEASE!!!

Answer 1

Did you find fog?

Answer 2

no @Prathamesh_M

Answer 3

To find fog, i.e., f(g(x)), you simply substitute g(x) in the place of x in f(x).

Answer 4

I got (2x^2+5x)=5/x(2x+5)
@Prathamesh_M

Answer 5

@phi

Answer 6

the say f(x) = 5/x
f ( g(x) ) means replace x with g(x)
f (g (x) ) = 5/g(x)

if we use the definition of g(x) = 2x^2+5x we get
\[ f(g(x)) = \frac{5}{ 2x^2+5x} \\ f(g(x)) = \frac{5}{ x(2x+5)} \]

is that what you got ?

Answer 7

yes

Answer 8

the domain are "allowed x values"

we usually assume all x values are valid, but we don't allow x values that cause trouble.
we get in trouble if we divide by 0 (so we don't allow it) or square root of a negative number

Answer 9

we don't have any square roots. but we do divide
what value of x would cause a divide by 0
any idea ?

Answer 10

using algebra we would solve the problem by asking what x's give us zero:
x ( 2x+5) = 0

Answer 11

to solve
x ( 2x+5) = 0

we use this idea:
if you multiply two numbers say "a" and "b", and get 0
a*b= 0
then we would say *either a is 0* or *b is 0*

in your problem we have "two numbers"
x * (2x+5) = 0
so either x is zero of (2x+5) is zero

Answer 12

I got x=0,-5/2 ?

Answer 13

yes. those are the two x values we exclude from the domain
i.e. the answer to this problem

Answer 14

Thanks for explaining it, you helped me out a lot :D