Question

1.) fungsi g ditentukan dengan rumus g(x)=ax + b.
diketahui g(5)= -11 dan g(-3) = 13. tentukan nilai a dan b, rumus fungsi serta nilai fungsi untuk x = 4.
jawab:

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Answer 1

G(-3) = ax + b
13 = a(-3) + b
13 = -3a + b

g(5) = ax + b
-11 = a(5) + b
-11 = 5a + b

eliminasikan

13=-3a + b
-11=5a + b
----------------- -
24 = -8a
24/-8= a
-3 = a

untuk cari b, substitusikan
13=-3a + b
13= -3(-3) + b
13 = 9 + b
4 = b

rumus fungsi
g(x) = ax + b
g(x) = -3x + 4

nilai fungsi x=4
g(4) = -3(4) + 4
= -12 + 4 = -8

Answer 2

G(x) = ax + b
g(5)= a(5) + b = 5a + b = -11
g(-3) = a(-3) + b = -3a + b = 13

eliminasi b, maka
8 a = -24
a = -24/8
a = -3

substitusi nilai a, maka
5a + b = -11
5(-3) + b = -11
-15 + b = -11
b = -11+15
b = 4

nilai a dan b :
-3 dan 4

rumus fungsi :
g(x) = ax + b
g(x) = -3x + 4

nilai fungsi untuk x = 4 ;
g(4) = -3(4) + 4
g(4) = -12 + 4
g(4) = -8