Question

Let F(x)=x2−20 and G(x)=14−x, how do you find(FG)(7)?

Answer 1

Solution:

Given f(x) = x²-20 ---(1)

g(x) = 14 - x -----(2)

i) f[g(x)]

= f[14-x]

= (14-x)² - 20

f(g(x)) = (14-x)²-20 ----(3)

Now ,

f(g(7)) = (14-7)² - 20

= 7² - 20

= 49 - 20

= 29

Therefore,

f(g(7)) = 29

••••

Answer 2

Answer: F = (2x - 20)/x  {{{ * = Multiplication }}}

G = (14 - x)/x

(FG)(7)

SUBSTITUTE  

((2x - 20)/x * (14 - x)/x)) * 7

(28x - 3x - 280 + 20x) * 7

(45x - 280) * 7

315x - 1960