Why is the middle term 2ab in (a+b)^2 and -2ab in (a-b)^2 when written in standard form

Step-by-step explanation:

You can try to expand, then you will get the middle term as 2ab or -2ab:

(a+b)² = (a+b)(a+b)

= a² + ab + ab + b²

= a² + 2ab + b²

As for the (a-b)², it will come in the same way :

(a-b)² = (a-b)(a-b)

= a² - ab - ab + b²

= a² - 2ab + b²

(Hope you can understand)

answer

explanation

the area of a circle is calculated using the formula

or

we can use any of the above formulae to calculate the required. preferably, let us use the latter since the diameter is

we substitute the diameter into the formula to get:

this is the exact value for the area of the circle.

the correct answer is a