Materi : Bentuk dan Persamaan Kuadrat

Nilai a

Titik ( Xp = -1 dan Yp = 3 )

Titik ( x = -2 dan y = 1 )

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y = a( x - Xp )² + Yp

1 = a( - 2 + 1 )² + 3

1 = a(-1)² + 3

a(1) = 1 - 3

[ a = -2 ]

Nilai c

Titik ( x = 0 dan y = 1 )

f(x) = ax² + bx + c

y = a(0)² + b(0) + c

c + 0 + 0 = 1

[ c = 1 ]

Nilai b

Titik ( x = -2 dan y = 1 )

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f(x) = ax² + bx + c

f(-2) = (-2)(-2)² + b(-2) + 1

y = (-2)(4) - 2b + 1

1 = - 8 - 2b + 1

2b = - 8 - 1 + 1

2b = -8

[ b = -4 ]

Hasil / Result :

{ a = -2, b = -4, c = 1 }

Bentuk Fungsi : f(x) = - 2x² - 4x + 1

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