diketahui rumus fungsi f(x)=2x-7 . jika f(a) = -1 dan f(4)= b, mak nilai 2a-b adalah.

F(x) = 2x-7
F(a) = 2 (-1) -7
= -2-7
= -9
F(b) = 2(4) -7
= 8-7
= 1

2a + b
2(-9) + 1
= -18 + 1
= -17

.. maybe sih.. maaf klo salah:")

f(a)=-1 
      = 2.-1 -7
      =-9
f(b)=4
      = 2.4-7
       =1
jadi 2.-9 -1= -19