please tolong dijawab kk dengan benar

Misal OP = r
P (x,y) --> r² = x² + y² dan y = 5 - 1/2 x²
r² = x² +(5 - 1/2 x²)²
r² = x² + 25 - 5x² + 1/4 x⁴
r² = 1/4 x⁴ - 4x²  + 25
OP = √ { 1/4 x⁴ - 4x² + 25 }

f(x)= 1/4 x⁴ - 4x² + 25
f'(x)= x³ -8x
f'(x)= 0 --> x (x² - 8) = 0
x = 0 atau x = 2√2

f(0)= 25
f(2√2) = 1/4 (8²)- 4(8) + 25 = 9
f(2) = 1/4(2⁴)  - 4(2²) + 25 =13

OP = √( 1/4 x⁴ - 4x² +25)
x= 0 --> OP =√25
x = 2√2 --> OP = √9
x = 2 --> OP = √13
jarak terpendek =OP = √9 = 3cm