nomor 3 dan 4 tolong ya kak......

Anggaplah sisi segitiga: a, b, dan c. a yang terpanjang, c yang terpendek.
a + b + c = 19a = 2c
a = b + c - 3;
masukkan a = 2c
2c = b + c - 3c = b - 3a + b + c = 19;
masukkan a = 2c2c + b + c = 19;
masukkan c= b - 32 (b - 3) + b + (b - 3) = 19
2b - 6 + b + b - 3 = 19
4b - 9 =19
4b = 28b = 7 cm
c = b - 3c = 7 - 3c = 4 cma = 2ca = 2 x 4a = 8 cm


x + y + z = 278
(1)60.000x + 35.000y + 25.000z = 13.000.000↔ 60x + 35y + 25z = 13.000
(2)x = 2y – 10
(3)Substitusikan persamaan
(3) ke (1)x + y + z = 278↔ 2y – 10 + y + z = 278↔ 3y + z = 278 + 10↔ z = 288 – 3y (4)Substitusikan (3) dan (4) ke
(2)60x + 35y + 25z = 13.000↔ 60(2y – 10) + 35y + 25(288 – 3y) = 13.000↔ 120y – 600 + 35y + 7.200 – 75y = 13.000↔ 80y = 6.400↔
y = 6.400 : 80 = 80
Substitusikan nilai y = 1.542,5 ke (3) dan (4)x = 2(80) – 10 = 150z = 288 – 3(80) = 48