Question

How does step 1 become 2 in this pic

Answer 1

As (a+b)²=a²+b²+2ab

And (a-b)²=a²+b²-2ab

(a+b)²-4ab=a²+b²+2ab-4ab=a²+b²-2ab=(a-b)²

Hope this would help you.

Answer 2

Answer:

(a- b )^ 2 = a^ 2 + b ^ 2 - 2ab....1

(a+ b ) ^ 2 = a^ 2 + b^ 2 + 2ab ....2

subtracting 4ab both side in eq 2

( a+ b ) ^ 2 - 4ab = a^ 2 + b ^ 2 + 2ab - 4 ab

(a+b )^ 2 - 4 ab = a^ 2+ b ^ 2 - 2ab

(a+ b)^ 2 - 4ab = ( a - b ) ^ 2 ........( see equation 1