Question

Suatu fungsi f dirumuskan dengan f (x)= ax+b , jika f(a) = 19 , f(b) = dan ab = -12 nilai f(a-b) =...... pakai rumus

Answer 1

F(x) =ax+b
f(a) = a^2+b = 19
f(b) = ab+b = -9
karena ab = -12
maka -12+b = -9
b =3
kemudian ke pers f(a)
a^2 + 3 = 19
a^2 = 16
a = -4 (4 tidak memenuhi karena ab = -12)
f(x) -4x + 3
f(a-b) = f(-4-3)
f(a-b) = f(-7)
f(a-b) = -4 (-7) + 3
f(a-b) = 28 + 3 = 31

Answer 2

F(a) = a(a)+b
19=a²+b

f(b) = a(b)+b
-9=ab+b

-9=ab+b
-9=-12+b
-b=-12+9
b=3

-9=ab+b
-9=a(3)+3
-9=3a+3
-3a=3+9
-3a=12
a=
a=-4

f(a-b)=a(a-b)+b
       =-4(-4-3)+3
       =-4(-7)+3
       =28+3
      = 31