Tentukan penyelesaian sistem persamaan brikut dengan metode subtitusi untuj x y e r 9. 3x + y = 7 dan 5x - 3y = 7 10. 2x - y = 18 dan 3x + 4y = 5

no. 9) 3x + y = 7 》 y = 7 - 3x
5x - 3y = 7
5x - 3(7 - 3x) = 7
5x - 21 + 9x = 7
5x + 9x = 7 + 21
14x = 28
x = 28/14 = 2
tinggal mencari y nya :
3x + y = 7
3(2) + y = 7
6 + y = 7
y = 7-6 = 1

no. 10) 2x - y = 18 》 y = 2x-18
3x + 4y = 5
3x + 4(2x-18) = 5
3x + 8x - 72 = 5
3x + 8x = 5+72
15x = 77
x = 77/15
tinggal mencari y nya :
2x - y = 18
2(77/15) - y = 18
154/15 - y = 18
-y = 18 - 154/15
y = 154/15 - 18
sayang angkanya gk enak

Materi : SPLDV

METODE SUBSTITUSI !
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9. [][][]
3x + y = 7 ....... [1]
5x - 3y = 7 ..... [2]

》3x + y = 7
》y = 7 - 3x

Substitusi ke persamaan 2 !
》5x - 3y = 7
》5x - 3(7 - 3x) = 7
》5x - 21 + 9x = 7
》14x = 7 + 21
》14x = 28
》x = 2

Substitusi Nilai x kesalah-satu persamaan !
》y = 7 - 3x
》y = 7 - 3(2)
》y = 7 - 6
》y = 1

Hp = {2 , 1}



10. [][][]
2x - y = 18 ........ [1]
3x + 4y = 5 ...... [2]

》2x - y = 18
》-y = 18 - 2x
》y = -18 + 2x

Substitusi Ke persamaan 2 !

》3x + 4y = 5
》3x + 4(-18 + 2x) = 5
》3x - 72 + 8x = 5
》11x = 5 + 72
》11x = 77
》x = 7

Substitusi Nilai x kesalah-satu persamaan !

》y = -18 + 2x
》y = -18 + 2(7)
》y = -18 + 14
》y = -4

Hp = {7 , -4}