jika f(x)=ax2 +bx + c,f (1)= 3, dan f(-1) = 3, a+c=...

f(x) = ax² + bx + c

f(1) = 3
a(1)² + b(1) + c = 3
a + b + c = 3

f(-1) = 3
a(-1)² + b(-1) + c = 3
a - b + c = 3

a + b + c = 3
a - b + c = 3
-------------------- +
2a + 2c = 6
a + c = 3