Artikel Matematika

What is square root of 4

It seems that after learning quadratic equation, some students confused about square root. They thought $\sqrt 4$ can be -2 or 2.

No! $\sqrt 4$ is $2$

But (you may say),  $(-2)^2$ is also 4. Doesn't it mean -2 is also $\sqrt 4$

Nope! By convention squared root of a positive number is always a positive number.

But, if you are asked to find x that fit in this equation $x^2 = 4$ the answer $x = \pm \sqrt 4$.

See here, the value of x that fit to that equation is $x = -\sqrt 4$ or $x= +\sqrt 4$ and $\sqrt 4$ is 2.

Solution to Singapore maths question that stumped the world

Singapore maths question stumped the world

The following question has stumped the world. It was circulated that this is a fifth grader exams question, but later verified that this is actually 14 year old questions

Problem

Albert and Bernard just became friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates.

May 15 May 16 May 19

June 17 June 18

July 14 July 16

August 14 August 15 August 17

What is 1 divided by 0?

$\frac 10 \neq \infty$

Some say 1 divided by 0 is infinity. They argue that when a number is divided by smaller number the result is bigger number. And if we divide a number with a very very very small number it will give a very very very big number. According to them zero is a very very very small number therefore 1 divided by 0 will give infinity (a very very very big number). Is that true? NO!

Limit and infinity

limit x mendekati 8

Just got this 'story' from twitland

After explaining concept of limit and give example as shown above, the teacher try to test students see if they understood. And the following is the student's answer

 

hmmm... something wrong?

Strange Division

8 divided by 2

I found an interesting "concept" of division on a Facebook timeline. I draw an image (above) to ilustrate it and save it here for future reference.

Problem:

What is 8 divided 2?

Answer:

It depends on how you divide it. If divided horizontally it becomes 0 each. But if it is divided vertically, it becomes 3.