Question

Jawaban dan cara penyelesaian no 23, 24, dan 25

Answer 1

23.
x^2 - 10x + 21 < 0
(x - 3)(x - 7) < 0
x1 = 3, x2 = 7

utk x < 0, HP = ? < x < ! . contoh : 3 < x < 7
utk x > 0, HP = x < ? atau x > ! . contoh : x < 3 atau x > 7

jadi, HP = {x | 3 < x < 7} (e)

24.
misal :
kue pisang cokelat = x
kue pisang keju = y

7x + 5y = 85.500
3x + 7y = 75.500 (c)

25.
misal :
apel = x
jeruk = y

2x + 3y = 57.000 (× 3)
3x + 5y = 90.000 (× 2)

6x + 9y = 171.000
6x + 10y = 180.000
_______________ -
-y = -9.000
y = 9.000

2x + 3(9.000) = 57.000
2x = 57.000 - 27.000
2x = 30.000
x = 30.000/2 = 15.000

x + y = 15.000 + 9.000 = 24.000
kembalian = 100.000 - 24.000 = Rp 76.000,- (d)

maaf kalo salah