Given :
What should be subtracted from a² – 7ab + 3b² to get – 4a² + 6ab + 3b² ?
Solution :
Let the required expression to be subtracted be x
⇢ a² – 7ab + 3b² – x = – 4a² + 6ab + 3b²
⇢ a² – 7ab + 3b² – (– 4a² + 6ab + 3b²) = x
⇢ a² – 7ab + 3b² + 4a² – 6ab – 3b² = x
Combining the like terms :
⇢ a² + 4a² – 7ab – 6ab + 3b² – 3b² = x
⇢ 5a² – 13ab = x
⇢ x = 5a² – 13ab
Therefore,
5a² – 13ab should be subtracted from a² – 7ab + 3b² to get – 4a² + 6ab + 3b².
