Search our library of A Level questions

Top answers

All subjects

A Level

¿Cuales son los problemas principales del turismo en Andalucía hoy en día?

Con respecto a una región tan popular como Andalucía, algunos problemas son inevitables. Por ejemplo, durante ciertos periodos del año los turistas superan en número los autóctonos y eso conlleva peligros...

Answered by Thomas W. • Spanish tutor

3043 Views

During the cardiac cycle , there is a delay between the excitation of the atria and excitation of the ventricles. Explain how this is achieved and why this delay is essential.

Excitation from SAN (sino-atrial node) spreads across atria, causing them to contract first. The excitation is conducted to the AV (atri...

Answered by Jane E. • Biology tutor

15309 Views

Find, without using a calculator, integral of 1/sqrt(15+2x-x^2) dx, between 3 and 5, giving your answer as a multiple of pi

To get the denominator into something usable, you have to complete the square so you have it in one of the forms you can use a trig or hyperbolic substitution for. The minus sign in front of the x2 means ...

Answered by Luke D. • Further Mathematics tutor

4953 Views

Integrate 2x/(x^2+3) using the substitution u=x^2+3

u=x² + 3

du/dx=2x

dx=du/2x

2x/(x²+3) dx becomes (2x/u) * (du/2x)

the 2x terms cancel out giving 1/u du

this integrates to ln(u)+c becoming ln(x

Answered by Tom S. • Maths tutor

14524 Views

If timber prices fall by 30%, what will be the expected % change in demand for timber in the economy if the Price Elasticity of Demand is -0.5, and explain the effect on revenue for a timber-selling firm.

Price Elasticity of Demand (PED) is a measure of the responsiveness of demand to a change in price. A PED of -0.5 suggests demand is price inelastic – as Price falls by 1%, Demand will increase by 0.5% (l...

Answered by Harry C. • Economics tutor

2060 Views