Jika 16x^2 - 49y^2 = 333 dan 4x - 7y = 9, maka... a. x > y b. x < y c. x = y d. x = 2y e. tidak dapat ditentukan

Bab Persamaan Kuadrat
Matematika SMP Kelas VIII

16x² - 49y² = 333
(4x + 7y) (4x - 7y) = 333
(4x + 7y) . 9 = 333
4x + 7y = 333 : 9
4x + 7y = 37

4x + 7y = 37
4x - 7y = 9
----------------- +
8x = 46
x = 5,75

4x - 7y = 9
4 . 5,75 - 7y = 9
7y = 23 - 9
y = 14 : 7
y = 2

maka, x = 5,75 dan y = 2
x > y

◎◎ A ◎◎

Mapel : Matematika
Kelas : VIII SMP
Bab : SPLDV

Pembahasan :
16x² - 49y² = 333
4²x² - 7²y² = 333
(4x)² - (7y)² = 333
(4x + 7y)(4x - 7y) = 333
(4x + 7y)(9) =333
4x + 7y = 37

Eliminasi...
4x + 7y = 37
4x - 7y = 9
———————— (-)
14y = 28
y = 2

Substitusi...
4x - 7y = 9
4x = 9 + 7y
4x = 9 + 7(2)
4x = 9 + 14
4x = 23
x = 23/4
x = 5,75

Diambil Kesimpulan bahwa x > y