P(x) = ax⁴ + bx³ + cx² + dx + e
P(1) = P(–1):
a + b + c + d + e = a – b + c – d + e
2b + 2d = 0
b + d = 0
P(2) = P(–2):
16a + 8b + 4c + 2d + e = 16a – 8b + 4c – 2d + e
16b + 4d = 0
4b + d = 0
{b + d = 0
{4b + d = 0
b = 0, d = 0
P(x) = ax⁴ + cx² + e
P(–x) = a(–x)⁴ + c(–x)² + e = ax⁴ + cx² + e = P(x)
P(–x) = P(x) при любом x
P(x) = ax⁴ + bx³ + cx² + dx + e
P(1) = P(–1):
a + b + c + d + e = a – b + c – d + e
2b + 2d = 0
b + d = 0
P(2) = P(–2):
16a + 8b + 4c + 2d + e = 16a – 8b + 4c – 2d + e
16b + 4d = 0
4b + d = 0
{b + d = 0
{4b + d = 0
b = 0, d = 0
P(x) = ax⁴ + cx² + e
P(–x) = a(–x)⁴ + c(–x)² + e = ax⁴ + cx² + e = P(x)
P(–x) = P(x) при любом x