Theory question 102
Algebraic ExpressionsGiven that y = [pr/m − p2r]−3/2, (a) make r the subject; (b) find the value of r when y = −8, m = 1 and p = 3.
Show the model answer
Model answer
(a) Raise both sides to the power −2/3: y−2/3 = pr/m − p2r = r(p − mp2)/m
r = my−2/3/(p − mp2) = m/(y2/3p(1 − mp))
(b) y2/3 = ((−8)1/3)2 = (−2)2 = 4
r = 1/(4 × 3 × (1 − 3)) = −1/24
Explanation
Undo the power −3/2 by raising both sides to −2/3.