Gambar berikut adalah sebuah model kerangka balok terbuat dari kawat dengan ukuran panjang (a + 5) cm, Iebar (a.-: 2) cm, dan tingginya a cm. Panjang kawat yang digunakan seluruhnya tidak lebih dari 108 cm b. Susun pertidaksamaan dalam a, kemudian selesaikanlah!

<p>Jawab: a ≤ 8&nbsp;</p><p>Pembahasan:</p><p>Ingat!</p><p>Jumlah panjang rusuk = (4×panjang)+(4×lebar)+(4×tinggi)</p><p>Dengan menggunakan konsep di atas, diperoleh</p><p>Panjang kawat yang digunakan adalah sama dengan jumlah dari seluruh panjang rusuk balok. Maka,</p><p>Panjang kawat ≤ 108&nbsp;</p><p>&nbsp;(4×panjang)+(4×lebar)+(4×tinggi) ≤ 108</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (4(a+5))+(4(a-2))+(4(a)) ≤ 108&nbsp;</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 4a+20+4a-8+4a ≤ 108&nbsp;</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 12a+12 ≤ 108</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;12a ≤ 96&nbsp;</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; a ≤ 8&nbsp;</p><p>Sehingga, nilai a yang memenuhi adalah &nbsp;a ≤ 8.</p><p>&nbsp;</p><p><strong><u>Jadi, jawaban yang benar adalah a ≤ 8.</u></strong></p>