absolute value

[imane81]

if absolute value(d-9) = 2d, then d=

a. -9
b.-3
c.1
d.3
e.9

The right answer is -9 or 3??
i would go for answer a which is d= -9 but please confirm

would actually like to know if an absolute value should always be taken for its positive value as it is a distance and a distance is always positive

[ajith]

if absolute value(d-9) = 2d, then d=

a. -9
b.-3
c.1
d.3
e.9

The right answer is -9 or 3??
i would go for answer a which is d= -9 but please confirm

would actually like to know if an absolute value should always be taken for its positive value as it is a distance and a distance is always positive

since absolute value always gives a positive value 2d should be positive, so should d

9-d =2d
d=3

or

d-9 =2d
or d= -9 which is not possible since in that case 2d will not be positive

[spoiler]hence d=3[/spoiler]

[money9111]

you got (d-9) because (9-d)*(-1)?

[ajith]

you got (d-9) because (9-d)*(-1)?

absolutely, d-9 can be negative or positive so, we have to consider both

[thephoenix]

ld-9l=2d--------->

+-(d-9)=2d----->

d=+3 or d=-9

now putting values back in eqn=for d=3 we get LHS=RHS

and for d=-9
lHS#RHS

hence d=3