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Tentukan himpunan penyelesaian persamaan kuadrat berikut dengan cara memfaktorkan! a.x² – 2x – 8 = 0. b.2x² + 7x + 6 = 8
Jawab:
(a.) Hp = {4, -2}
(b.) Hp = {-³/₂, -2}
Penjelasan :
(a.) x² – 2x – 8 = 0
-> Ax² + Bx + C = 0
A = 1, B = -2, C = -8
p dan q akar-akar persamaan
p+q = -B/A, pq = C/A
p+q = -(-2/1), pq = -8/1
p+q = 2 pq = -8
4 – 2 = 2 4(-2) = -8
p = 4, q = -2
Hp = {p, q}
Hp = {4, -2}
——————————————-
2x² + 7x + 6 = 8 mungkin
maksudnya 2x² + 7x + 6 = 0
karena 2x² + 7x + 6 = 8 hanya
dapat dicari lewat kuadrat
sempurna dan rumus abc saja
(b.) 2x² + 7x + 6 = 0
(2÷2)x² + ⁷/₂ x + ⁶/₂ = 0
-> x² + ⁷/₂ x + ⁶/₂ = 0
-> x² + ⁷/₂ x + ⁶⁽²⁾/₂₍₂₎ = 0
-> x² + ⁷/₂ x + ¹²/₄ = 0
-> Ax² + Bx + C = 0
A = 1, B = ⁷/₂, C = ¹²/₄
p dan q akar-akar persamaan
p+q = -B/A, pq = C/A
p+q = -(⁷/₂)/1, pq = (¹²/₄)/1
p+q = -⁷/₂, pq = ¹²/₄
-³/₂+(-⁴/₂) = -⁷/₂ -³/₂(-⁴/₂) = ¹²/₄
p = -³/₂, q = -⁴/₂
p = -³/₂, q = -2
Hp = {p, q}
Hp = {-³/₂, -2}
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