Question

tolong bntu dgan langkah langkah​

Answer 1

Fungsi Kuadrat

no. 7

f(x) = ax² - 5x + 23

f(3) = -10

3² a - 5.3 + 23 = -10

9a - 15 + 23 = -10

9a + 8 = -10

a = (-10 - 8)/9

a = -2

no. 8

f(x) = x² + bx - c

f(3) = 3² + 3b - c = 10

3b - c = 10 - 9

3b - c = 1 ... (1)

f(5) = 5² + 5b - c = 32

5b - c = 32 - 25

5b - c = 7 ... (2)

dari persamaan (1) dan (2)

5b - c = 7

3b - c = 1 -

2b = 6

b = 3

3b - c = 1

3.3 - c = 1

9 - c = 1

c = 8

Nilai b dan c berturut-turut : 3 dan 8

Answer 2

Jawaban:

7.

f(x) = ax² - 5x + 23

f(3) = -10

masukan nilai x = 3

f(3) = ax² - 5x + 23

-10 = a.3² - 5.3 + 23

-10 = 9a - 15 +23

-10 = 9a + 8

9a + 8 = -10

9a = -10 - 8 (nilai +8 pindah ruas menjadi -8)

9a = -18

a = -18 / 9

a = -2

8.

f(x) = x² + bx - c

jika:

f(3) = 10

=====> f (3) = 3² + 3b - c = 10

= 9 + 3b - c = 10

= 3b - c = 10 - 9

= 3b - c = 1

f(5) = 32

=====> f(5) = 5² + 5b - c = 32

= 25 + 5b - c = 32

= 5b - c = 32 - 25

= 5b - c = 7

maka:

3b - c = 1

5b - c = 7

------------ -

8b = -6 ( nilai c nya hilang)

b = -6/8 = -3/4

jadi nilai b yaitu -¾

kemudian cari nilai c

pakai saja 1 persamaan dengan memasukkan nilai b = -¾

3b - c = 1

(3 . -¾ ) - c = 1

-9/4 - c = 1

c = 9/4 - 1

c = 9/4 - 4/4

c = 5/4 atau 1¼

jadi nilai c yaitu 1¼