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The equation (k+3)x^2 + 6x + k =5 has two distinct real solutions for x. Prove that k^2-2k-24<0

We argue using the discriminant of a quadratic polynomial. For a quadratic ax^2 + bx + c=0, the discriminant D is D = b^2 - 4ac. When this quadratic has two distinct real roots, we have that D > 0. So ...

Answered by Huw D. • Maths tutor

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I don't understand why the function "f(x)=x^2 for all real values of x" has no inverse. Isn't sqrt(x) the inverse?

I don't understand why the function "f(x)=x^2 for all real values of x" has no inverse. Isn't sqrt(x) the inverse?
I like to think of a function a bit like a machine. It takes in a number, ...

Answered by Benjamin M. • Maths tutor

4180 Views

Integrate exp(2x)cos(8x) by parts

Let u=exp(2x) and v'=cos(8x)From these you can obtain u' and vu=2exp(2x) and v=1/8 sin(8x)Formula: integral(uv'dx)=uv-integral(vu'dx)=1/8 exp(2x)sin(8x)-integral(1/4 sin(8x)exp(2x))=1/8exp(2x)sin(8x)+1/16...

Answered by Chloe D. • Maths tutor

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Solve the equation 8x^6 + 7x^3 -1 = 0

The first thing to recognise is this is a quadratic in disguise, therefore we can rewrite the equation in terms of a new variable y.
Where y=x³
The equation then becomes 8y²

Answered by Kelan P. • Maths tutor

6938 Views

Integrate sinxcosx dx

Since the question is a trigonometry question, we shall use integration by recognisation, in which case, we found out that the derivative of sin x is cos x.Therefore by chain rule, we can integrate the fu...

Answered by Harris L. • Maths tutor

4210 Views