Panjang diagonal diagonal persegi (3x+5)cm dan (5x-9)cm luas daerah persegi tersebut adalah....cm

3x+5 = 5x-9
3x - 5x = -9-5
-2x = -14
x = -14/-2 = 7
d = 3(7)+5 = 21+5 = 26 cm
s = (26/2)√2 = 13√2

Luas = s² = (13√2)²
= 169 x 2
= 338 cm²