jika f(×) = 2×^2+5×-7 dan g(×) = 3x-12, maka nilai (g o f)(2)??

jawab

f(x) = 2x² + 5x - 7
g(x) = 3x - 12

gof(2) = g { f(2) }
= g { 2(2²) + 5(2) - 7 }
= g {8+10-7}
= g (11)
= 3(11) - 12
= 33-12
= 21

[tex]gof(x) = g(f(x)) \\ = g(2 {x}^{2} + 5x - 7) \\ = 3(2 {x}^{2} + 5x - 7) - 12 \\ = 6 {x}^{2} + 15x - 21 - 12 \\ = 6 {x}^{2} + 15x - 33 \\ \\ gof(2) = 6 {(2)}^{2} + 15(2) - 33 \\ = 6(4) + 15(2) - 33 \\ = 24 + 30 - 33 \\ = 21[/tex]
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