# Partial differential equation formed from the equation z=(x+a)(y+b) is: (i) z=p+q (ii) z=p+q+k (iii) z=pq (iv) None of these

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z=(x+a)(y+b)

differentiate z w.r.t ,x and y partially

`(delz)/(delx)=y+b`

`(delz)/(dely)=x+a`

`But`

`(delz)/(delx)=p`

`(delz)/(dely)=q`

`pq=(x+a)(y+b)=z`

Thus part (iii) is correct.