Question

Evaluate (1•8×2•2) by using suitable identity (write the identity used).​

Answer 1

we used the identity of x+(a+b) x+ab

Answer 2

Answer:

1.8 x 2.2 cannot be evaluated in this form. We can further expand the identity as follows:

(2 - 0.2) x (2 + 0.2)

This is in the form of the identity - (a + b) x (a - b)

(a + b) x (a - b) = a² - b²

Similarly,

(2 - 0.2) x (2 + 0.2)

= 2² - (0.2)²

= 4 - 0.04

= 3.96

Verification:

Let's multiply the values, 1.8 x 2.2 normally.

1.8 x 2.2 = 3.96

Hence, it is verified.

$\boxed{\begin{minipage}{7 cm}\boxed{\bigstar\:\:\textbf{\textsf{Algebric\:Identity}}\:\bigstar}\\\\1)\bf\:(A+B)^{2} = A^{2} + 2AB + B^{2}\\\\2)\sf\: (A-B)^{2} = A^{2} - 2AB + B^{2}\\\\3)\bf\: A^{2} - B^{2} = (A+B)(A-B)\\\\4)\sf\: (A+B)^{2} = (A-B)^{2} + 4AB\\\\5)\bf\: (A-B)^{2} = (A+B)^{2} - 4AB\\\\6)\sf\: (A+B)^{3} = A^{3} + 3AB(A+B) + B^{3}\\\\7)\bf\:(A-B)^{3} = A^{3} - 3AB(A-B) + B^{3}\\\\8)\sf\: A^{3} + B^{3} = (A+B)(A^{2} - AB + B^{2})\\\\\end{minipage}}$