Diketahui auatau fungsi dengan rumus f(x)=ax+b dengan f(1)=-2dan f(4)=19,maka nilai dari f(-2)=...

f(1) = a(1) + b
-2 = a + b

f(4) = a(4) + b
19 = 4a + b

a + b = -2
4a + b = 19
---------------- (-)
-3a = -21
a = 7

a + b = -2
7 + b = -2
b = -9

f(-2) = a(-2) + b = 7(-2) + (-9) = -14 + (-9) = -23

Mapel : Matematika

Kelas : 10

Bab : Relasi dan Fungsi
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f(x) = ax + b

→ f(1) = -2

→ f(4) = 19


Ditanya → f(-2)

Jawaban :
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→ f(1) = a + b = -2

→ f(4) = 4a + b = 19
.................................... -

-3a = -21

a = 21/3
a = 7 ✔

→ a + b = -2
→ 7 + b = -2
→ b = -2 - 7
→ b = -9


Maka,
f(-2) = 7(-2) + (-9)

f(-2) = -14 - 9

f(-2) = -23