(i) L.H.S = (3x + 7)^{2} − 84x

= (3x)^{2} + 2(3x)(7) + (7)^{2} − 84x

= 9x^{2} + 42x + 49 − 84x

= 9x^{2} − 42x + 49

R.H.S = (3x − 7)^{2} = (3x)^{2 }− 2(3x)(7) +(7)^{2}

= 9x^{2} − 42x + 49

L.H.S = R.H.S

(ii) L.H.S = (9p − 5q)^{2} + 180pq

= (9p)^{2} − 2(9p)(5q) + (5q)^{2} − 180pq

= 81p^{2} − 90pq + 25q^{2} + 180pq

= 81p^{2} + 90pq + 25q^{2}

= (9p)^{2} + 2(9p)(5q) + (5q)^{2}

= 81p^{2} + 90pq + 25q^{2}

L.H.S = R.H.S