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Pertanyaan

Jika x → 0 lim ​ 3 − Ax + B ​ x ​ = 2 , maka ....

Jika , maka ....

  1. A² = –B

  2. 3A = B

  3. 3A + B = 0

  4. A = 3B

  5. A = B²

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A. Abdul

Master Teacher

Jawaban terverifikasi

Jawaban

jawaban yang tepat adalah C.

jawaban yang tepat adalah C.

Pembahasan

Misalkan f(x) = x dan . Perhatikan bahwa f(0) = 0. Jikag(0) ≠ 0, maka . Namun . Sehingga haruslah g(0) = 0. Maka Sehingga Maka didapatkan A = –3 dan B = 9. Perhatikan setiap pilihan yang tersedia. A)A²= –B A² = (–3)² = 9 –B = –9 Sehingga A² ≠ –B (pernyataan A salah) B) 3A = B 3A = 3(–3) = –9 B = 9 Sehingga 3A ≠ B (pernyataan B salah) C) 3A + B = 0 3A + B = 3(–3) + 9 = –9 + 9 = 0 Sehingga 3A + B = 0 (pernyataan C benar) D) A = 3B A = –3 3B = 3(9) = 27 Sehingga A ≠ 3B (pernyataan D salah) E) A = B² A = –3 B² = 9² = 81 Sehingga A ≠ B² (pernyataan E salah) Jadi, jawaban yang tepat adalah C.

Misalkan f(x) = x dan begin mathsize 14px style straight g open parentheses straight x close parentheses equals 3 minus square root of Ax plus straight B end root end style.

Perhatikan bahwa f(0) = 0. Jika g(0) ≠ 0, maka begin mathsize 14px style limit as straight x rightwards arrow 0 of invisible function application fraction numerator straight x over denominator 3 minus square root of Ax plus straight B end root end fraction equals 0 end style.

Namun begin mathsize 14px style limit as straight x rightwards arrow 0 of invisible function application fraction numerator straight x over denominator 3 minus square root of Ax plus straight B end root end fraction not equal to 0 end style. Sehingga haruslah g(0) = 0.

Maka

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell straight g open parentheses 0 close parentheses end cell equals 0 row cell 3 minus square root of straight A open parentheses 0 close parentheses plus straight B end root end cell equals 0 row cell 3 minus square root of straight B end cell equals 0 row cell negative square root of straight B end cell equals cell negative 3 end cell row cell square root of straight B end cell equals 3 row straight B equals 9 end table end style 

Sehingga

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell limit as straight x rightwards arrow 0 of invisible function application fraction numerator straight x over denominator 3 minus square root of Ax plus 9 end root end fraction end cell equals 2 row cell limit as straight x rightwards arrow 0 of invisible function application open parentheses fraction numerator straight x over denominator 3 minus square root of Ax plus 9 end root end fraction times fraction numerator 3 plus square root of Ax plus 9 end root over denominator 3 plus square root of Ax plus 9 end root end fraction close parentheses end cell equals 2 row cell limit as straight x rightwards arrow 0 of invisible function application fraction numerator straight x open parentheses 3 plus square root of Ax plus 9 end root close parentheses over denominator 9 minus open parentheses Ax plus 9 close parentheses end fraction end cell equals 2 row cell limit as straight x rightwards arrow 0 of invisible function application fraction numerator straight x open parentheses 3 plus square root of Ax plus 9 end root close parentheses over denominator 9 minus Ax minus 9 end fraction end cell equals 2 row cell limit as straight x rightwards arrow 0 of invisible function application fraction numerator straight x open parentheses 3 plus square root of Ax plus 9 end root close parentheses over denominator negative Ax end fraction end cell equals 2 row cell limit as straight x rightwards arrow 0 of invisible function application fraction numerator 3 plus square root of Ax plus 9 end root over denominator negative straight A end fraction end cell equals 2 row cell fraction numerator 3 plus square root of straight A open parentheses 0 close parentheses plus 9 end root over denominator negative straight A end fraction end cell equals 2 row cell fraction numerator 3 plus square root of 9 over denominator negative straight A end fraction end cell equals 2 row cell fraction numerator 3 plus 3 over denominator negative straight A end fraction end cell equals 2 row cell fraction numerator 6 over denominator negative straight A end fraction end cell equals 2 row straight A equals cell negative 3 end cell end table end style 

Maka didapatkan A = –3 dan B = 9.

Perhatikan setiap pilihan yang tersedia.

A)  A² = –B
     A² = (–3)² = 9
    –B = –9
Sehingga A² ≠ –B (pernyataan A salah)

B) 3A = B
     3A = 3(–3) = –9
       B = 9
Sehingga 3A ≠ B (pernyataan B salah)

C) 3A + B = 0
     3A + B = 3(–3) + 9 = –9 + 9 = 0
Sehingga 3A + B = 0 (pernyataan C benar)

D) A = 3B
     A = –3
   3B = 3(9) = 27
Sehingga A ≠ 3B (pernyataan D salah)

E) A = B²
     A = –3
    B² = 9² = 81
Sehingga A ≠ B² (pernyataan E salah)

Jadi, jawaban yang tepat adalah C.

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