Question

Tolong dijawab yah nomor 18 &19 pakai cara

Answer 1

18. 
3/4 x + 1/6 y = 4 --> kalikan 12 --> 9x + 2y = 48
1/2 x - 2/3 y = - 2--> kalikan 6 --> 3x - 4y = -12

9x + 2y = 48
9x - 12y = - 36
.....................(-)
14 y = 84 --> y = 6
3x - 4y = -12
3x - 4(6) = -12
3x = -12 + 24
3x = 12
x = 4

nilai 2x - y = 2(4) - (6)  = 2

19.  soal kurang data soal...
misal nya  AB = 12 cm
BD² = CD² - BC²
BD² = CD²- (AB²+ AC²)
BD² = CD² - AB² - AC²
BD² = 25² - 12² -16²
BD² = 625 - 144 - 256 
BD²  = 225
BD = 15