Pliss,yang pakar mtk smp tolong bantu isiin dong no 10,11,14,15
aanoktafia
10. pertama kita mencari nilai x keliling persegi panjang = 2p + 2l 94 = 2 (5x+2) + 2 (2x+3) 94 = 10x + 4 + 4x +6 94 = 10x + 4x + 4 + 6 94 = 14x +10 14x = 94 - 10 14x = 84 x = 84/14 x = 6 lalu ganti x dengan 6 panjang = 5x + 2 = 5(6) +2 = 30 + 2 = 32 cm
lebar = 2x + 3 = 2(6) + 3 = 12 + 3 = 15 cm
jadi panjang = 32 cm dan lebar = 15 cm ......(C)
11. 3x + 6 = 5x + 20 3x - 5x = 20 - 6 -2x = 14 x = 14/-2 x = -7 maka nilai x +12 = -7 + 12 = 5 .....(B)
15. 3x + y = -10 | x 3 | 9x + 3y = -30 2x + 3y = -16 | x 1 | 2x + 3y = -16 dikurangi untuk menghilangkan y 7x = - 14 x = -14/7 x = -2 lalu masukkan nilai x ke salah satu persamaan 3x + y = -10 3(-2) + y = -10 -6 + y = -10 y = -10 +6 y = -4
keliling persegi panjang = 2p + 2l
94 = 2 (5x+2) + 2 (2x+3)
94 = 10x + 4 + 4x +6
94 = 10x + 4x + 4 + 6
94 = 14x +10
14x = 94 - 10
14x = 84
x = 84/14
x = 6
lalu ganti x dengan 6
panjang = 5x + 2
= 5(6) +2
= 30 + 2
= 32 cm
lebar = 2x + 3
= 2(6) + 3
= 12 + 3
= 15 cm
jadi panjang = 32 cm dan lebar = 15 cm ......(C)
11. 3x + 6 = 5x + 20
3x - 5x = 20 - 6
-2x = 14
x = 14/-2
x = -7
maka nilai x +12 = -7 + 12 = 5 .....(B)
15.
3x + y = -10 | x 3 | 9x + 3y = -30
2x + 3y = -16 | x 1 | 2x + 3y = -16
dikurangi untuk menghilangkan y
7x = - 14
x = -14/7
x = -2
lalu masukkan nilai x ke salah satu persamaan
3x + y = -10
3(-2) + y = -10
-6 + y = -10
y = -10 +6
y = -4
maka 3x - 2y = 3(-2) - 2(-4) = -6 + 8 = 2 .... (B)