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Tritium is a radioactive nucleide with a half life of 4500 days, determine the time for 90% of it to decay.

We know that the number of undecayed nuclei, N, is given by N=N₀e^{-lambda t}. From this, by setting N=N₀/2 we know at this point that t= T_0.5 (the half life) and ...

Answered by Luke C. • Physics tutor

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I decrease a number by 26%, the answer is 9 x10^-7, what was the original number?

The number has been decreased by 26%, this means that the original number is 100-26=74% of the original value.

Therefore 9 x 10^-7 = 0.74 x N, where N is the original number.

Henc...

Answered by Luke C. • Maths tutor

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How do I integrate the volume of revolution between 0 and pi of y=sin(x)?

To integrate the volume of revolution first imagine a thin disk around the x-axis which we want to know the volume of: Volume=area x height. The area of a circle is given by pi r^2 and in our case let us ...

Answered by Luke C. • Maths tutor

3930 Views

Solve: x^2-7x+6=0

Factorise the equation and then equate each set of brackets to 0 to obtain both possible solutions.

By factorising: (x-6)(x-1)=0

Therefore: x=6 or x=1

Answered by Phoebe G. • Maths tutor

6004 Views

Line AB has equation 4x+5y+2=0. If the point P=(p, p+5) lies on AB, find P . The point A has coordinates (1, 2). The point C(5, k) is such that AC is perpendicular to AB. Find the value of k.

i) Well, if point P lies in AB, then the value of its x and y coordinates have to fulfill the condition imposed by equation AB. Therefore, substituting the x value p for x and the y value p+5 for y:

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Answered by Javier L. • Maths tutor

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