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Where does the quadratic formulae come from?

The general form of a quadratic equation is, ax 2 +bx + c = 0. If we divide all terms by a we get, x 2 +(b/a)x + c/a = 0. then by completing the square we get (x+(b/2a)) 2 + c/a - b 2 /4a 2 = 0 which rearang...
BO
Answered by Benjamin O. • Maths tutor
4689 Views

Can I take a derivative at x=0 for the function f(x) = |x| ?

Just because a function is continuous at a point, that doesn't mean it has a derivative at that point. If a function is differentiable on an interval, then it is continuous on that interval, but the reverse ...
TD
Answered by Tutor68168 D. • Maths tutor
6804 Views

Rationalise the denominator of \frac{6}{\sqrt{2}}.

When rationalising, multiply the fraction by the denominator - so what that means is multiply the fraction by the square rooted number over the square rooted number. The numerators then multiply to give 6 mu...
AR
Answered by Akash R. • Maths tutor
6141 Views

Using the "complete the square" method, solve the following x^2 +4x - 21 =0

x 2 +4x-21= 0, This can be factorised into brackets as shown: (x+2) 2 - 4 - 21 = 0 SImplified, so all x's are on one side of the equation: (x+2) 2 = 25, Removing square root, DONT FORGET "±" : (x+2...
CS
Answered by Charlotte S. • Maths tutor
6723 Views

Differentiate y= 8x^2 +4x +5

dy/dx= (2 * 8)x (2-1) +4 = 16x + 4
JJ
Answered by Juevaneeta J. • Maths tutor
4383 Views