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**Place the last two terms of the following expressions in parentheses preceded by a minus sign: (i) x + y âˆ’ 3z + y (ii) 3x âˆ’ 2y âˆ’ 5z âˆ’ 4 (iii) 3a âˆ’ 2b + 4c âˆ’ 5 (iv) 7a + 3b + 2c + 4 (v) 2a^{2} âˆ’ b^{2} âˆ’ 3ab + 6 (vi) a^{2} + b^{2}^{ }âˆ’ c^{2} + ab âˆ’ 3ac**

We have

(i) x + y âˆ’ 3z + y = x + y âˆ’ (3z - y )

(ii) 3x âˆ’ 2y âˆ’ 5z âˆ’ 4 = 3x - 2y - (5z + 4)

(iii) 3a âˆ’ 2b + 4c âˆ’ 5 = 3a - 2b - (- 4c + 5)

(iv) 7a + 3b + 2c + 4 = 7a + 3b - (- 2c - 4)

(v) 2a^{2} âˆ’ b^{2} âˆ’ 3ab + 6 = 2a^{2} âˆ’ b^{2} âˆ’ (3ab - 6)

(vi) a^{2}^{ }+ b^{2} âˆ’ c^{2} + ab âˆ’ 3ac = a^{2}^{ }+ b^{2} âˆ’ c^{2} - (- ab + 3ac)

**Write each of the following statements by using appropriate grouping symbols: (i) The sum of a âˆ’ b and 3a âˆ’ 2b + 5 is subtracted from 4a + 2b âˆ’ 7. (ii) Three times the sum of 2x + y âˆ’ {5 âˆ’ (x âˆ’ 3y)} and 7x âˆ’ 4y + 3 is subtracted from 3x âˆ’ 4y + 7. (iii) The subtraction of x^{2} âˆ’ y^{2} + 4xy from 2x^{2} + y^{2} âˆ’ 3xy is added to 9x^{2} âˆ’ 3y^{2} âˆ’ xy.**

(i) The sum of a âˆ’ b and 3a âˆ’ 2b + 5 = {(a - b) + (3a âˆ’ 2b + 5)}.

This is subtracted from 4a + 2b - 7.

Thus, the required expression is {4a + 2b - 7) - {(a - b) + (3a âˆ’ 2b + 5)}.

(ii) Three times the sum of 2x + y âˆ’ {5 âˆ’ (x âˆ’ 3y)} and 7x âˆ’ 4y + 3 = 3[(2x + y) âˆ’ {5 âˆ’ (x âˆ’ 3y)} + (7x âˆ’ 4y + 3)].

This is subtracted from 3x - 4y +7.

Thus, the required expression is (3x - 4y +7) - 3[(2x + y) âˆ’ {5 âˆ’ (x âˆ’ 3y)} + (7x âˆ’ 4y + 3)].

(iii) The product of subtraction of x^{2} âˆ’ y^{2} + 4xy from 2x^{2} + y^{2} âˆ’ 3xy is given by {(2x^{2} + y^{2} âˆ’ 3xy) - (x^{2} âˆ’ y^{2} + 4xy)}.

When the above equation is added to 9x^{2} âˆ’ 3y^{2} âˆ’ xy, we get

{(2x^{2} + y^{2} âˆ’ 3xy) - (x^{2} âˆ’ y^{2} + 4xy)} + (9x^{2} âˆ’ 3y^{2} âˆ’ xy)