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Consider the functions f(x)=3x^2 - 5 and g(x)= √x -5 +2

how can i find
f(5)
g(5)
f(4)
g(4)
describe the domain of f(x)
describe the domain of g(x)
why is the domain of one of these functions more restructive than the other?

User Wali
by
7.3k points

2 Answers

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F(5):


f(5) = 3(5)^(2) - 5


f(5) = 15^(2) - 5


f(5) = 225 - 5


f(5) = 220


G(5):


g(5) = √(5) - 5 + 2


g(5) = 2,24 - 5 + 2


g(5) = -2,76 + 2


g(5) = -0,76


F(4):


f(4) = 3(4)^(2) - 5


f(4) = 12^(2) - 5


f(4) = 144 - 5


f(4) = 139


G(4):


g(4) = √(4) - 5 + 2


g(4) = 2 - 5 + 2


g(4) = -3 + 2


g(4) = -1



Hope it helped,


BioTeacher101

User Wadesworld
by
8.1k points
4 votes

f(x) = 3x² - 5

f(5) = 3(5)² - 5 → f(5) = 3(25) - 5 → f(5) = 75 - 5 → f(5) = 70

f(4) = 3(4)² - 5 → f(4) = 3(16) - 5 → f(4) = 48 - 5 → f(5) = 43

DOMAIN of f(x): All real numbers (because there are no restrictions on "x")

************************************************************

g(x) =
√(x - 5) + 2

g(5) =
√(5 - 5) + 2 → g(5) =
√(0) + 2 → g(5) = 2

g(4) =
√(4 - 5) + 2 → g(4) =
√(-1) + 2 → g(4) = no real solutions

DOMAIN of g(x): x ≥ 5 (because you cannot take the square root of a negative number)


User Alexis Leclerc
by
7.9k points

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