For f(x) = 1 - 3x^2, g(x) = sqrt[4 - x], find (f o g)(2) and

[gemma]

I need to check if these are right..

For the first one:
1- 3(4-x) = 1 - 12 + 3 x = -11 + 3(2) = -5

and the second:

(square root of 4-(1-3x^2))
(square root of 4-(1-3(-2)^2)
sqrt(4-(1-3(4))
sqrt(4-(1-12)
sqrt(4-(-11))
answer: sqrt(15)

Thanks!

 

[stapel]

You can work strictly-numerically, too. :wink:

1) (f o g)(2) = f(sqrt[4 - (2)]) = f(sqrt[2])

. . . . . . . . . .= 1 - 3(sqrt[2])²

. . . . . . . . . .= 1 - 3(2) = 1 - 6 = -5

2) (g o f)(-2) = g(1 - 3(-2)²) = g(1 - 3(4))

. . . . . . . . . . .= g(1 - 12) = g(-11)

. . . . . . . . . . .= sqrt[4 - (-11)] = sqrt[15]

Good work!

Eliz.