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A note was played on a a keyboard. The frequency of the note was 440 Hz. (a) What does a frequency of 440 Hz mean? (b) The sound waves produced by the keyboard travel at a speed of 340 m/s. Calculate the wavelength of the note.

(a) A frequency of 440 Hz means that a single trough and peak of the sound wave oscillates 440 times per second or equally that 440 sound waves are produced by the keyboard per second (This is because the SI...
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Answered by Ifan W. • Physics tutor
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How do you solve the simultaneous equations 3x + 4y = 5 and 2x – 3y = 9

We label each equation 3x + 4y = 5 (1) 2x – 3y = 9 (2) We now want to get rid of one of the variables (x or y). Lets get rid of x: We need (1) and (2) to have the same number of x's so we multiple (1) by 2 a...
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Answered by Sahiti S. • Maths tutor
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If x = cot(y) what is dy/dx?

Here we will use: cot(x) = cos(x)/sin(x) cosec 2 (x) = 1 + cot 2 (x) Chain rule : dy/dt * dt/ dx = dy/ dx Product rule : d/dx (u v) = u dv/dx + v*du/dx x = cot(y)= cos(y)/sin(y) dx/dy = -cos(y) ( cos(y) / si...
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Answered by Sahiti S. • Maths tutor
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Find the complex number z such that 5iz+3z* +16 = 8i. Give your answer in the form a + bi, where a and b are real numbers.

Firstly, we note that z being a complex number can be expressed in the form z = a + bi. If we then take the complex conjugate of this expression, the real numbers remain the same (as they are their own c con...
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What is the Current Account

The current account is a section in the Balance of Payments, which shows a country's transactions with goods, services and income. It is made up of four different parts. 1) The balance of trade in goods 2) T...
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Answered by Sahiti S. • Economics tutor
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