For f(x)=2x+1 and g(x)=x^2 -7 , find (f times g)(x)

2x³ + x² - 14x - 7

Step-by-step explanation:

The product of f(x) and g(x) is

(2x + 1)(x² - 7)

Each term in the second factor is multiplied by each term in the first factor

2x(x² - 7) + 1 (x² - 7) ← distribute both parenthesis

= 2x³ - 14x + x² - 7

= 2x³ + x² - 14x - 7 ← in standard form

hello from mrbilldoesmath!

answer:   (7x + 6y) ( 49x^2 - 42xy + 36y^2)

discussion:

in general, the factorization of a^3 + b^3 is

a^3 + b^ 3 = (a + b) ( a^2 - ab + b^2)

in our case note that 343 = 7^3 and 216 = 6^3 so the equation becomes:

343x^3 + 216y^3 = (7x)^3 + (6y)^3

if you think of a (above) as 7x and b as 6y the factorization becomes

343x^3 + 216y^3 =

((7x + 6y) (   (7x)^2 - 7x*6y + (6y)^2)   =

(7x + 6y) ( 49x^2 - 42xy + 36y^2)

you,

mrb

(a + b) (a^2 - a b + b^2)