2012 DSE Maths Paper 2 Q25

L1：ax+y-b=0
L2：cx+y-d-0


(I)
Slope of L1 > 0
-a > 0
a < 0

∴(I) is correct


(II)
Slope of L1 < Slope of L2
-a < -c
a > c

∴(II) is wrong


(III)
y-intercept of L1 > y-intercept of L2
b > d

∴(III) is correct


(IV)
x-intercept of L1 < x-intercept of L2
b/a < d/c
bc < ad
ad > bc

∴(IV) is correct


ANS.=C

2015-04-08 15:23:09 補充：
For the general form of a linear equation:
Ax+By+C=0

Slope= -A/B
x-intercept= -C/A
y-intercept= -C/B

*remember that all has (-)