Question

Kak please bantuin yaa....no. 12-14
12.tentukan himpunan penyelesaian dari persamaan berikut.
a.2x-6=9x+8
b.2- 2/3x =4
c.2x-3/3 + 4x+4/2 =2x+3

13.suatu bilangan jika dikalikan 4 ,kemudian dikurangi 6 dieroleh hasil 54,berapakah bilangan yang dimaksud itu?

14.harga suatu buku tiga kali harga 1 pensil .bila harga satu buku rp.1.200.00,maka tentukan harga 8 pensil.

Answer 1

12a. 2x - 6 = 9x + 8
12a. -6 - 8 = 9x - 2x
12a. -14 = 7x
12a. -14/7 = x
12a. -2 = x

12b. 2 - 2/3x = 4
12b. -2/3x = 4 - 2
12b. -2/3x = 2
12b. x = 2 * -3/2
12b. x = -3

12c. 2x - 3/3 + 4x + 4/2 = 2x + 3
12c. 2x - 1 + 4x + 2 = 2x + 3
12c. 6x + 1 = 2x + 3
12c. 6x - 2x = 3 - 1
12c. 4x = 2
12c. x = 4/2
12c. x = 2

13. 4x - 6 = 54
13. 4x = 54 + 6
13. 4x = 60
13. x = 60/4
13. x = 15

14. x = 3y
14. 1.200 = 3y
14. 1.200/3 = y
14. 400 = y
14. z = 8y
14. z = 8 * 400
14. z = 3.200

Answer 2

nomor 12 a
2x - 6 = 9x + 8
2x - 9x = 8 + 6
   -7x = 14
      x = -2

nmr 12 b
2 - 2/3x = 4
-2/3x = 4 - 2
-2/3x = 2
x      = 2 X -3/2
     x = -6/2
     X = -3

nmr 12 c
2x - 3/3 + 4x + 4/2 = 2x + 3
2x - 1 + 4x + 2 = 2x + 3
2x + 4x - 2x = 3 + 1 - 2
     4x = 2
       x = 2/4
     x  = 1/2

nomor 13
4x - 6 = 54
4x = 54 + 6
 4x = 60
   x = 60/4
   x = 15

nomor 14
misl harga buku = x
harga pensil = y

maka :
x = 3y
1.200 = 3y
   y = 1200/3
   y = 400

jadi harga 1 pensil = 400
harga 8 pensil = 400 x 8 = 3.200