yang tau minta tolong dong..

<p>Jawaban yang tepat adalah <strong>A. f(x) = -2x² + 3x + 4</strong></p><p>&nbsp;</p><p>Pembahasan :</p><p>Rumus umum fungsi kuadrat&nbsp;</p><p><strong>f(x) = ax² + bx + c</strong></p><p>&nbsp;</p><p>Melalui titik (0,4)</p><p>f(x) = ax² + bx + c</p><p>4 = a(0)²+ b(0) + c</p><p>4 = c</p><p>c = 4</p><p>&nbsp;</p><p>Melalui titik (-1,-1)</p><p>f(x) = ax² + bx + c</p><p>-1 = a(-1)²+ b(-1) + c</p><p>-1 = a - b + c &nbsp; (karena c = 4)</p><p>-1 = a - b + 4</p><p>-1 - 4 = a - b</p><p>a = -5 + b &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;(1)</p><p>&nbsp;</p><p>Melalui titik (1,5)</p><p>f(x) = ax² + bx + c</p><p>5 = a(1)²+ b(1) + c</p><p>5 = a + b + c</p><p>5 = a + b + 4</p><p>5 - 4 = a + b</p><p>1 = a + b &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (2)</p><p>&nbsp;</p><p>Substitusikan persamaan (1) ke persamaan (2)</p><p>1 = a + b &nbsp;&nbsp;</p><p>1 = -5 + b + b</p><p>1 + 5 = 2b</p><p>b = 6/2 = 3</p><p>&nbsp;</p><p>Substitusikan b = 3 ke persamaan (1)</p><p>a = -5 + b</p><p>&nbsp; &nbsp;= -5 + 3</p><p>&nbsp; &nbsp;= -2</p><p>&nbsp;</p><p>Persamaan kuadrtanya&nbsp;</p><p>Masukkan a = -2, b = 3 dan c = 4 ke rumus umum</p><p>&nbsp;f(x) = ax² + bx + c</p><p><strong>f(x) = -2x² + 3x + 4</strong></p><p>&nbsp;</p><p>&nbsp;</p>