Diketahui suatu fungsi f dinyatakan dengan rumus f(x)=px+ 9 Jika f(−6)=32 dan f(4)=−8 Tentukan rumus fungsi f(x) !

<p>Jawaban: f(x) = -4x + 8.</p><p>Asumsikan rumus f(x) = px + q</p><p>&nbsp;</p><p>Ingat konsep berikut:</p><p>Bentuk umum fungsi linear adalah f(x) = ax + b. dengan a, b bilangan real dan a≠0.</p><p>Nilai fungsi &nbsp;untuk &nbsp;adalah&nbsp;</p><p>&nbsp;</p><p>Diketahui suatu fungsi f dinyatakan dengan rumus f(x) = px + q Jika f(−6) = 32 dan f(4) = −8, maka:</p><p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; f(−6) = 32</p><p>p(-6) + q = 32</p><p>&nbsp; -6p + q = 32&nbsp;&nbsp;&nbsp;&nbsp; …(1)</p><p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp;f(4) = −8</p><p>&nbsp;p(4) + q = −8</p><p>&nbsp; &nbsp; 4p + q = −8&nbsp;&nbsp;&nbsp; &nbsp;…(2)</p><p>&nbsp;</p><p>Perhatikan persamaan (1):</p><p>-6p + q = 32</p><p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; q = 32 + 6p</p><p>&nbsp;</p><p>Substitusikan ke persamaan (2)</p><p>4p + q = −8&nbsp;&nbsp;&nbsp;</p><p>4p + 32 + 6p = −8&nbsp;&nbsp;&nbsp;</p><p>10p + 32 = −8&nbsp;&nbsp;&nbsp;</p><p>10p = −8 – 32</p><p>10p = -40</p><p>p = -4</p><p>&nbsp;</p><p>Substitusikan nilai p:</p><p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; q = 32 + 6p</p><p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; q = 32 + 6(-4)</p><p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; q = 32 – 24</p><p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; q = 8</p><p>&nbsp;</p><p>Sehingga rumus fungsinya: (substitusikan nilai p dan q)</p><p>f(x) = px + q</p><p>f(x) = -4x + 8</p><p>&nbsp;</p><p>Jadi, rumus fungsi f(x) = -4x + 8.</p>