Fungsi f(x) =ax+b, jika f(-5)=15 dan f(5)=-5..maka nilai dari f(-1) adalah

f(x) = ax + b
f(- 5) = - 5a + b = 15
f(5) = 5a + b = - 5

- 5a + b = 15
5a + b = - 5
_________—
- 10a = 20
a = - 2

5a + b = - 5
- 10 + b = - 5
b = - 5 + 10
b = 5

f(- 1)
= - a + b
= 2 + 5
= 7

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