Ukuran panjang (2x+4) cm dan lebar (2x-1)cm jika keliling 70 cm,maka Luas persegi panjang tersebut adalah...

[tex]k = 2 (p + l) \\ 70 = 2 \times (2x + 2x + 4 - 1) \\ 70 = 2 \times (4x + 3) \\ 70 = 8x + 6 \\ 64 = 8x \\ x = 8 \\ p = 2x + 4 = 2 \times 8 + 4 = 20\\ l = 2x - 1 = 2 \times 8 - 1 = 15 \\ luas = p \times l \\ = 15 \times 20 = 300[/tex]