3^x+9^x=90. nilai x adalah...
Matematika
Angelicadfs
Pertanyaan
3^x+9^x=90. nilai x adalah...
1 Jawaban
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1. Jawaban dnnyz07
Eksponen
3^x + 9^x = 90
3^x + (3²)^x = 90
3^x + (3^x)² = 90
misal 3^x = a
a + a² = 90
a² + a - 90 = 0
(a + 10)(a - 9) = 0
a = -10 .. TM
a = 9
3^x = 9
x = 2