2017 · Q12
If A : B = 3 : 4, then what is the value of the expression ((3A²+4B)/(3A-4B²)) ?
Elementary MathematicsRatio and Proportion
- A43/55
- B-43/55
- C47/55
- DCannot be determined
Explanation
Put A = 3k, B = 4k. The expression becomes (27k² + 16k)/(9k − 64k²) = (27k+16)/(9−64k), which still depends on k. The ratio A:B = 3:4 does not fix k, so the value cannot be determined: option D. Any numerical option would require assuming a value of k.