Question

What should be taken away from  3a2 – 4b2 + 5ab + 20 to obtain –a2 – b2 +6ab + 20?​

Answer 1

Answer:

Let the expression to be subtracted be equal to X. It contains terms a², b², and ab.

\begin{gathered}3 a^2 - 4 b^2 + 5 a b - X = - a^2 - b^2 + 6 a b \\ \end{gathered}

3a

2

−4b

2

+5ab−X=−a

2

−b

2

+6ab

Take X to the right side, and Bring the expression on the right to the left side of equal to.

\begin{gathered}3 a^2 - 4 b^2 + 5 a b + a^2 + b^2 - 6 a b = X \\ \end{gathered}

3a

2

−4b

2

+5ab+a

2

+b

2

−6ab=X

Add the similar terms

\begin{gathered}(3+1)a^2 + (-4+1)b^2 + (5-6) ab = X \\ \\ 4 a^2 -3b^2 -ab = X, OR,\ \ \ \ \ \ X = 4a^2 - 3 b^2 - ab \\\end{gathered}

(3+1)a

2

+(−4+1)b

2

+(5−6)ab=X

4a

2

−3b

2

−ab=X,OR, X=4a

2

−3b

2

−ab