2019 · Q38
If (4a + 7b)/(4c + 7d) = (4a - 7b)/(4c - 7d), then which one of the following is correct?
Elementary MathematicsRatio and Proportion
- Aa/b = c/d
- Ba/b = c/b
- Ca/b = d/c
- D4a/7b = c/d
Explanation
By componendo–dividendo, [(4a+7b)+(4a−7b)]/[(4a+7b)−(4a−7b)] equals the same expression in c, d: 8a/14b = 8c/14d, i.e. a/b = c/d.