Question

Multiply the following:
i) $-3x^{2}y,(5y-xy)$
ii) $7pqr,(p-q+r)$
[2 marks]
[NCERT-Exemplar-Q83(v, vii)]
[ <!--td {border: 1px solid #cccccc;}br {mso-data-placement:same-cell;}--> Multiplication ​of algebraic ​expressions]

Answer 1

i) Given expressions are: $-3x^{2}y$ and $5y-xy$
According to the question,
$-3x^{2}y\times (5y-xy)=(-3x^{2}y\times 5y)+(3x^{2}y\times xy)=-15x^2{y}^2+3x^3{y}^2$
[1 mark]

ii) Given expressions are: $7pqr$ and $(p-q+r)$
$\therefore 7pqr\times (p-q+r)=(7pqr\times p)-(7pqr\times q)+(7pqr\times r)=7p^{2}qr-7p{q}^{2}r+7pq{r}^2$
[1 mark]