Diketahui sistem persamaan 4x - y = 18 dan 3x + 2y = 19.Nilai 4x + 7y = A.-27 B.27 C.34 D.43

Kelas 8 Matematika
Bab SPLDV

4x - y = 18
y = 4x - 18

3x + 2y = 19
3x + 2 (4x - 18) = 19
3x + 8x - 36 = 19
11x = 19 + 36
x = 55/11
x = 5

y = 4x - 18
y = 4 . 5 - 18
y = 20 - 18
y = 2

4x + 7y
= 4 . 5 + 7 . 2
= 20 + 14
= 34

4x-y=18 [×3] 12x-3y=54
3x+2y=19 [×4] 12x+8y=76
------------------ -
-11y= -22
y= 2
4x-y=18
4x - 2=18
4x= 18+2
4x=20
x=5

nilai 4x + 7y = 4.5 + 7.2
= 20 + 14
= 34
jawabanya C
maaf kalau salah