tolong bantu gan nomer 11-20 aja pake cara

12) f( x ) = 4x - 7
f( 3) = 4(3) - 7 = 12 - 7 = 5 ( D )

13) f(x) = 3x + 1
f(2) = 3(2) + 1 = 6 + 1 = 7 ( C )

14) f(x) = ax + b
f(3) = 3a + b = 5
f(-2) = - 2a + b = - 5
------------------------------(-)
5a = 10
a = 2
3a + b = 5
3(2) + b = 5
6 + b = 5
b = 5 - 6
b = - 1
f(x) = 2x - 1 ( B )

15) y = 2x - 1
m = 2 ( D )

16) m = ( y2 - y1 ) / ( x2 - X1 )
m = ( - 2 - 0 ) / ( 4 - 0 )
m = - 2 / 4
m = - ½ ( C )

17) y - y1 = m ( x - X1 )
y - 5 = ½ ( x - 3 )
y = ½ x - 3/2 + 5 ( dikali 2)
2y = x - 3 + 10
2y = x + 7 ( C )

18)( y - y1) / ( y2 - y1 ) = ( x - X1 ) / ( x2 - X1 )
( y - 1 ) / ( - 7 - 1 ) = ( x - 2 ) / ( - 2 - 2)
( y - 1 ) / - 8 = ( x - 2 ) / - 4
- 4 ( y - 1 ) = - 8 ( x - 2)
- 4y + 4 = - 8x + 16
- 4y = - 8x + 16 - 4
- 4y = - 8x + 12 ( disederhanakan)
y = 2x - 3 ( A )

19) 5x - 2y = 8
- 2y = - 5x + 8
m = - 5/-2
m = 5/2
sejajar m1 = m2 = 5/2
pers garis
y - y1 = m ( x - X1 )
y + 5 = 5/2 ( x - 3 )
y = 5/2 x - 15/2 - 5 ( dikali 2)
2y = 5x - 15 - 10
2y = 5x - 25
- 5x + 2y + 25 = 0
5x - 2y - 25 = 0 ( D )