Solve the equation: 4x2 = 36 how do i solve this?

Question

zehanz · Answer

4x²=36.
So 4 times a certain number is 36, that means that number can only be 9.
But... the number is not x, it is x², so now you still need to solve: 

x²=9. You now have to think what number(s) is (are) 9 when squared...

anonymous · Answer

3

anonymous · Answer

?

anonymous · Answer

it could be 3, or it could be $-3$

zehanz · Answer

-3

zehanz · Answer

(-3)²=(-3)*(-3)=9

anonymous · Answer

$$4x^2=36$$divide by 4 get 
$$x^2=9$$so $x$ could be $3$ since $3^2=9$ or $x$ could be $-3$ because 
$(-3)^2=9$ too

zehanz · Answer

@satellite73: In this case I have used the "thumb"-method: put your thumb on x² and ask yourself: 4 times what is 36? This method is used to solve equations in a more informal way.

 Why? Because it is a simple equation and there is no need to bring out all the equipment ;)

(Of course I know that you can always use your method).