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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
6901 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
6285 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
6846 Views

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

dy/dx= (2 * 8)x (2-1) +4 = 16x + 4
JJ
Answered by Juevaneeta J. • Maths tutor
4461 Views

Express (3 + 13x - 6x^2)/(2x-3) in the form Ax + B + C/(2x - 3)

The answer is -3x + 2 + 9/(2x-3). That is A = -3, B = 2 and C = 9. I will use the whiteboard during my interview to explain the working.
SM
Answered by Sam M. • Maths tutor
5808 Views