Question

Select a suitable identity and the product of the following equation:
$(7d-9e)(7d-9e)$ is $49d^2-126de+81e^2$

• A. True
• B. False

Answer 1

The correct option is A True

We have $(7d-9e)(7d-9e)$

This is of the form $(a-b)(a-b)$ i.e. $(a-b{)}^2$ where $7d=a,9e=b$

We have, $(a-b{)}^2=a^2-2ab+b^2$

$\therefore (7d-9e{)}^2=7d^2-2\times 7d\times 9e+9e^2$

$=49d^2-126de+81e^2$

Hence, it is true.