a is directly proportional to b and inversely proportional to the square of c. if a=7 when b=9 and c=6, find a when b=4 and c=8
=
a = k·
Substitute the information from the situation when all the variables
are given:
7 = k·
Solve for k:
7 = k·
7 = k·
Multiply both sides by 4
28 = k
Substitute the value of k in the equation:
a = k·
a = 28·
Substitute the information from the other situation when all
the variables BUT ONE are given:
a = 28·
a = 28·
Solve for the missing variable, which in this case is "a":
a = 28·
a = 28·
a =
a =
a = or
a = 1.75
Edwin