Est. 1998 — 27 years of woodworking knowledge
One more extra
This one is simple. Can you figure it out?
Given:
-20 = -20
1. Rewrite the two given values as differences:
16-36 = 25-45
2. Replace the four values from step 1 as products:
4� - (9x4) = 5� - (9x5)
3. Add 81/4 to each side:
4� - (9x4) + 81/4 = 5� - (9x5) + 81/4
4. Factor both sides of the equation:
(4 - 9/2)� = (5 - 9/2)�
5. Take the square root of each side:
4 - 9/2 = 5 - 9/2
6. Add 9/2 to each side and we end up with:
4 = 5
Spoiler
Re Step 5: Which one?
;-)
An easy one, but it is hidden a bit better than the 1=2 puzzle don't you think?
Re: ;-)
Yes, I was SURE I was going to find division by zero, then stumbled on this.
Re: One more extra
One thing that usually stumbles mathematics beginners is the fact that by definition the square root of x^2 is the absolute value of x, not just x.
(Here x^2 means x to the second power.)
A nit pick
"by definition the square root of x^2 is the absolute value of x, not just x."
I don't disagree, when spedifying _THE_ square root, but I find it clearer to specify that as the "principal square root" or "positive square root", since -|x| is also _A_ square root of x^2.