Question

3. Dadas as funções definidas por
$f(x) = 2 {x}^{2} - 6x - 4 \: e \: g(x) = - 3 {x}^{2} - 5x + 1 \: calcule :$
a) f(3)

b) f(-2)

c) f(0)

d) f(-0,2)

e) g(1)

f) g(-4)

g) g(0)

h)
$( \frac{1}{2} )$
​

Answer 1

f(x) = 2x² - 6x - 4 e g(x) = - 3x² - 5x + 1

a. *** f(3)

f(3) = 2 . 3² - 6 . 3 - 4

f(3) = 2 . 9 - 18 - 4

f(3) = 18 - 18 - 4

f(3) = 0 - 4

f(3) = - 4

b. *** f(- 2)

f(- 2) = 2 . (- 2)² - 6 . (- 2) - 4

f(- 2) = 2 . 4 + 12 - 4

f(- 2) = 8 + 12 - 4

f(- 2) = 20 - 4

f(- 2) = 16

c. *** f(0)

f(0) = 2 . 0² - 6 . 0 - 4

f(0) = 2 . 0 - 0 - 4

f(0) = 0 - 4

f(0) = - 4

d. *** f(- 0,2)

f(- 0,2) = 2 . (- 0,2)² - 6 . (- 0,2) - 4

f(- 0,2) = 2 . 0,04 + 1,2 - 4

f(- 0,2) = 0,08 + 1,2 - 4

f(- 0,2) = 1,28 - 4

f(- 0,2) = - 2,72

e. *** g(1)

g(1) = - 3 . 1² - 5 . 1 + 1

g(1) = - 3 . 1 - 5 + 1

g(1) = - 3 - 5 + 1

g(1) = - 8 + 1

g(1) = - 7

f. *** g(- 4)

g(- 4) = - 3 . (- 4)² - 5 . (- 4) + 1

g(- 4) = - 3 . 16 + 20 + 1

g(- 4) = - 48 + 20 + 1

g(- 4) = - 48 + 21

g(- 4) = - 27

g. *** g(0)

g(0) = - 3 . 0² - 5 . 0 + 1

g(0) = - 3 . 0 - 0 + 1

g(0) = - 3 + 0 + 1

g(0) = 0 + 1

g(0) = 1

h. *** g(1/2)

g(1/2) = - 3 . (1/2)² - 5 . 1/2 + 1

g(1/2) = - 3 . 1/4 - 5 . 0,5 + 1

g(1/2) = - 3 . 0,25 - 2,5 + 1

g(1/2) = - 0,75 - 2,5 + 1

g(1/2) = - 3,25 + 1

g(1/2) = - 2,25

atte. yrz