fungsi dinyatakan dg rumus f(x)=x*+ax+b dg fungsi f(2)=5 dan f(1)= 0 tentukan nilai a dan b, bentuk fungsinya, nilai f(4)

f(x) = x² + ax + b
f(2) = 4 + 2a + b = 5
f(1) = 1 + a + b = 0

4 + 2a + b = 5
2a + b = 5 - 4
2a + b = 1

1 + a + b = 0
a + b = 0 - 1
a + b = - 1

2a + b = 1
a + b = - 1
_______—
a = 2

a + b = - 1
2 + b = - 1
b = - 1 - 2
b = - 3

f(4) :
x² + ax + b
= 4² + 8 - 3
= 16 + 5
= 21

Maaf Kalau Salah

f(2) = 2² + 2a+ b
5 = 4 + 2a+b
1 = 2a+b..1)

f(1) = 1²+a+b
0 = 1+a+b
-1 = a+b...2)

1 = 2a+b
-1= a+ b
--------- -
2 = a ⇒ -1 = 2 +b 
              -3 = b
f(4) = 4²+ 2.4+ (-3)= 16+8-3 = 21