fungsi f(x) = ax+b mempunyai f(-1)=2 dan f(1)=8 nilai f(4)adalah

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

f(1) = a(1) + b
8 = a + b

2 = -a + b
8 = a + b _
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-6 = -2a
3 = a

8 = 3 + b
8 - 3 = b
5 = b

f(4) = 3(4) + 5
f(4) = 12 + 5
f(4) = 17