Himpunan penyelesaian bilangan bulat yang memenuhi persamaan (x−8)^(x²− 9) =(x−8)^(3−x) adalah ….

Himpunan penyelesaian bilangan bulat yang memenuhi persamaan (x−8)^(x²− 9) =(x−8)^(3−x) adalah ….

Jawabannya adalah {-4, 3, 7, 9}

Ingat pada persamaan eksponen f(x)^g(x) = f(x)^h(x)
berlaku :
i) g(x) = h(x)
ii) f(x) = 1
iii) f(x) = -1 dengan syarat g(x) dan h(x) keduanya genap atau keduanya ganjil
iv) f(x) = 0 dengan syarat g(x) dan h(x) positif

Pembahasan :
i) x² – 9 = 3 – x
x² + x – 9 – 3 = 0
x² + x – 12 = 0
(x + 4) (x – 3) = 0
x = -4 atau x = 3

ii) x – 8 = 1
x = 1 +8
x = 9

iii) x – 8 = -1
x = -1 + 8
x = 7
Syarat kedua pangkat genap/ganjil.
x² – 9 = 7² – 9 = 49 – 9 = 40 (genap)
3 – x = 3 – 7 = -4 (genap)
Karena keduanya genap, makan x = 7 merupakan penyelesaian persamaan tersebut.

iv) x – 8= 0
x = 8
Syarat kedua pangkat positif :
x² – 9 = 8² – 9 = 64 – 9 = 55 > 0
3 – x = 3 – 8 = -5 < 0
Karena nilai 3 – x < 0 maka tidak memenuhi persyaratan, sehingga x = 8 bukan merupakan penyelesaian

Jadi himpunan penyelesaian persamaan di atas adalah {-4, 3, 7, 9}

Baca Juga :  Complete the sentences with a form of the verb in parentheses. Three hundred and fifty years ago, people (1. make) /made/ their own clothes. They (2. have, not) _____ machines for making clothes. There (3. be, not) _____ any clothing factories. People (4. tear) _____ homemade clothes that were sewn by hand. Today, very few people (5. make) _____ their own clothes. Clothing (6. come) _____ ready-made from factories. People (7. buy) _____ almost all their clothes from stores. The modern clothing industry (8. be) _____ international. As a result, people from different countries often (9. wear) _____ similar clothes. For example, people in many different countries throughout the world (10. wear) _____ jeans and t-shirts. However, some regional differences in clothing still (11. exist) _____ for instance, people of the Arabian deserts (12. wear) _____ loose, flowing lobes to protect themselves from the heat of the sun. In parts of Northern Europe, fur hats (13. be) _____ common in the winter. In the future, there (14. be, probably) _____ fewer and fewer differences in clothing. People throughout the world (15. wear) _____ clothes from the same factories. (16. We all, dress) _____ in the future? TV shows and movies about the future often (17. show) _____ everybody in a uniform of some kind. What (18. you, think) _____? Number 18