I will now prove that 21 Your assignment is to tell me what

I will now prove that 2=1. Your assignment is to tell me what went wrong. This is true for any real numbers A and B, you need to tell me which step is algebraically invalid and why:

a=b

a^2=ab

a^2-b^2=ab-b^2

(a+b)(a-b)=b(a-b)

a+b=b

b+b=b

2b=b

2=1

Solution

Step 4 is algebraically invalid.

Reason,

Since in step 1, we assumed that a = b, then

a - b = 0

Now in step 4, we are dividing both sides by (a - b), which is zero

And we know that if we divide by zero, then that is not defined.