Square root of -4? ?

Question

Im doing quadratic equations for the start of my A-Level maths.

the equation is x^2-4x = 0 which i have put into (x-2)^2=x^2-4x+4

this then goes into (x-2)^2-4=0 --> (x-2)^2=4 so this would mean x-2=+/-square root of 4 (+ or - because it is a quadratic) because of this x = +/- square root of 4 + 2.. +square root of 4 + 2 is 4, thats simple.... but what is the - square root of 4?

Answer 1

The square root of a negative number is a complex number that is part "real" part imaginary. The imaginary part is represented by the letter "i". i is defined to be equal to the square root of -1. This means that i^2 (i squared) is equal to -1.

√-4 =  ÃƒÂ¢Ã‚ˆÂš-1 * √4 =

√-1 = i  ÃƒÂ¢Ã‚ˆÂš4 = 2

therefore √-4 = 2i



Checkout: http://mathforum.org/library/drmath/view...

Later info: Look at Joel's answer above ... he's right, I think that u r asking the wrong question.

good luck

Answer 2

The two square roots of 4 are 2 and -2

x - 2 = 2 or x - 2 = -2, so

x = 4 or x = 0

(The real question you are asking is not about the square root of -4, but about the neg. square root of 4.)

Answer 3

x^2-4x= 0

x(x-4) = 0

x = 0 or 4 <-- It's that simple.

Answer 4

(x-2)^2=4

x-2=+_2

x=2_+2

x=0 and x=4

negative square root of 4 is 2i

Answer 5

x² - 4x = 0

x (x - 4) = 0

x = 0 , x = 4

Answer 6

The negative square root of 4 is just -2, since (-2)^2 = 4, so letting x - 2 = -2 gives x = 0 (which is the other solution to your original equation).  

As your title you wrote "square root of -4", which is actually something else.  sqrt(-4) = 2sqrt(-1) = 2i, where i is the imaginary unit, but I don't think you were actually asking for this.  Just be careful, because the square root of -4 is not the same as the negative square root of 4.

Answer 7

The square root of -4 is 2i.

If you take the square root of a negative number you will get an immaginary number.