Question

Q.UGAS
a×a+b×a=27,JIKA NILAI a=b-3
Maka nilai b adalah?

Answer 1

Jawab:
b = 6, b = -³/₂

Penjelasan:
a×a+b×a=27,
--> a(a+b) = 27 (pers i)
JIKA NILAI a=b-3
--> a = b-3 (pers ii)
Maka nilai b adalah?

a(a+b) = 27
Substitusi pers i dgn pers ii
(b-3)(b-3+b) = 27
(b-3)(2b-3) = 27
2b²-3b-6b+9 = 27
2b²-3b-6b+9-27 = 0
2b²-9b-18 = 0
b²-9b-18(2) = 0
b²-9b-36 = 0
(2b-12)(2b+3) = 0
2b = 12, 2b = -3
b = ¹²/₂, b = -³/₂
b = 6, b = -³/₂

(Xcvi)

Answer 2

Penjelasan dengan langkah-langkah:

DUO VARIABEL

a×a + b×a = 27, a = b – 3

a² + ab = 27

(b – 3)² + b(b – 3) = 27

b² – 6b + 9 + b² – 3b = 27

2b² – 9b = 27 – 9

2b² – 9b – 18 = 0

(2b + 3)(b – 6) = 0

b = –3/2 atau b = 6

b = –3/2

a = –3/2 – 3

a = –4½

a² + ab = 27

(–9/2)² + (–9/2)×(–3/2) = 27

81/4 + 27/4 = 27

108/4 = 27 ✔

b = 6

a = 6 – 3

a = 3

a² + ab = 27

3² + 3×6 = 27

9 + 18 = 27 ✔

jadi,

nilai b = –3/2 atau b = 6