Question

A + 2b + 3c = 12
2ab + 3ac + 6bc = 48
maka nilai a + b + c =...

Answer 1

Misal
x = a
y = 2b
z = 3c

x + y + z = 12

xy + yz + zx = 48

(x + y + z)² = x² +y² +z² +2(xy + yz + zx )

12² = x² +y² +z²+ 2(48)

144 = x² +y² +z² + 96

x² +y² +z² + 96 = 144

x² +y² +z² = 48 hal ini menyebabkan

x² +y² +z² = xy + yz + zx

x = y = z = 4

subtitusikan ke pemisalan

didapat a = 4, b = 2, c = 4/3

maka a + b + c = 4 + 2 + 4/3 = 22/3