Question

Help please.

Let f(x) = 3x + 2 and g(x) =7x + 6. Find f ·g and its domain.

A.
21x^2 +32x + 12; all real numbers except x = -6/7
B.
6x^2 + 4x + 42; all real numbers except x = ­2/3
 
C.
 21x^2 + 32x + 12; all real numbers
 
D.
 6x^2 + 4x + 42; all real numbers

Answer 1

the domain will be the numbers you can use for x and not get a undefined thing like division by 0 or square root of a negative number


(f*g)(x)=f(x) times g(x)=(3x+2) times (7x+6)=(3x+2)(7x+6)=
`21x^2+14x+18x+12=21x^2+32x+12`

the domain is all real numbers because we can't find any values of x that make a division by 0 or square root of a negative

answer is C