# Q.5 What should be taken away from$$3x^2 – 4y^2 + 5xy + 20$$to obtain $$– x^2 – y^2 + 6xy + 20?$$

$$3x^2 – 4y^2 + 5xy + 20 – m = -x^2 – y^2 + 6xy + 20$$
$$m= 3x^2 – 4y^2 + 5xy + 20 – (-x^2 – y^2 + 6xy + 20)$$
$$m= 3x^2 – 4y^2 + 5xy + 20 + x^2 + y^2 – 6xy – 20$$
$$m = 3x^2 + x^2 – 4y^2 + y^2 + 5xy – 6xy + 20 – 20$$
$$m = 4x^2 – 3y^2 – xy$$