Question

Jika f(x)=ax2+bx+c dan f(1)=3 dan f(-1)=3, maka (a+c) sama dengan...
tulis jawaban+caranya juga ya

Answer 1

F(x) = ax^2 + bx + c
f(1) = 3
f(1) = a(1)^2 + b(1) + c = 3
f(1) = a + b + c = 3

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

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

jadi,a+c = 3

Answer 2

F(x) = ax^2 + bx + c
f(1) = a(1)^2 + b(1) + c = 3 ... (1)

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

eliminasi persamaan 1 dan 2
a + b + c = 3
a - b + c = 3
2b = 3
b = 3/2.

substitusi nilai b ke persamaan 1.
a + b + c = 3
a + c = 3 - b
a + c = 3 - 3/2
a + c = 6/2 - 3/2
a + c = 3/2.