Question

Tolong bantu pakai cara

Answer 1

Jawaban:

b. -43

Penjelasan dengan langkah-langkah:

4x - 2y + z = -19........(1)

3x + y - 3z = - 8.........(2)

2x + 5y + z = 15........(3)

eliminasi (1) dan 2

4x - 2y + z = - 19....| x 3 |

3x + y - 3z = - 8.......| x 1 |

12x - 6y + 3z = - 57

3x + y - 3z = - 8

------------------------------- +

15x - 5y + 0 = - 65

15x - 5y = - 65

3x - y = - 13...............(4)

eliminasi (1) dan (3)

4x - 2y + z = - 19

2x + 5y + z = 15

-------------------------- --

2x - 7y + 0 = - 34

2x - 7y = - 34.............(5)

eliminasi (4) dan 5

3x - y = - 13...........| x 7 |

2x - 7y = - 34.........| x 1 |

21x - 7y = - 91

2x - 7y = - 34

--------------------------- --

19x + 0 = - 57

x = -57/19

x = - 3....masukan nilai x ke (4)

3x - y = - 13

3(-3) - y = - 13

-9 - y = - 13

-y = -13 + 9

-y = - 4

y = 4.....nilai x dan y masukan ke (1)

4x - 2y + z = -19

4(-3) - 2(4) + z = - 19

-12 - 8 + z = - 19

z = -19 + 12 + 8

z = 1

jadi : x = -3, y = 4, z = 1

5x - 9y + 8z

= 5(-3) - 9(4) + 8(1)

= -15 - 36 + 8

= - 43