Question

3x + 4y - 11z = 0
5y - 6z + 8x = 0
7z- 8x - 13y = -26.
solve by cross-multiplication method​

Answer 1

Answer:

x = 1,611

y = 3.351

z = 0.779

Step-by-step explanation:

3x + 4y - 11z = 0..... (1)

5y - 6z + 8x = 0

8x + 5y - 6z = 0 ........ (2)

7z- 8x - 13y = -26

-8x - 13y + 7z = -26 ........ (3)

Elimination 2 and 3

8x + 5y - 6z = 0

-8x - 13y + 7z = -26

________________+

-8y + z = -26 ...................(4)

Elimination 1 and 2

3x + 4y - 11z = 0 | ×8 |

8x + 5y - 6z = 0 | ×3 |

24x + 32y - 88z = 0

24x + 15y - 18z = 0

_______________--

17y - 70z = 0 ....................(5)

Elimination 4 and 5

-8y + z = -26 | ×70 |

17y - 70z = 0 | ×1 |

-560y + 70z = -1820

17y - 70z = 0

_________________+

-543y = -1820

y = 1820/543

y = 3.351

Elimination 4 and 5

-8y + z = -26 | ×17 |

17y - 70z = 0 | ×8 |

-136y + 17z = -442

136y - 560z = 8

_______________+

-543z = -434

z = -434/543

z = 0.779

Subsitution y and z

3x + 4y - 11z = 0

3x + 4(3.351) - 11(0.779) = 0

3x + 13.404 - 8,569 = 0

3x + 4,835 = 0

x = 4,835/3

x = 1,611