Объяснение:
16х² - (4х-5)² = 15
16х² - (16х²-40х+25) = 15
16х² - 16х² +40х - 25 = 15
40х = 15 + 25
х = 40:40
х = 1
64х² - (3-8х)² = 87
64х² -(9-48х+64х²) = 87
64х² - 9 + 48х - 64х² = 87
48х = 87 + 9
х = 96 : 48
х = 2
