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If the fourth term in an arithmetic sequence is, u4 = 12.5, the tenth is u10 = 27.5. Find the common difference and the 20th term.

The equations for an arithmetic sequences are 1) Un = u1 + (n - 1)d 2) Sn = n/2(2*u1 + (n-1)d) 3) Sn = n/2(u1 + un)

The first step is to calculate the common difference, d. This is done using the f...

Answered by Ndalukile K. • Maths tutor

2732 Views

Solve these simultaneous equations: 3y + x = 18 and x - 4y = -10.

Write x in terms of y using one of the equations. Then substitute it in the second equation, which is then only in terms of y. Find y. Then you can easily find x.

Answer: x = 6 and y = 4.

Answered by Tess E. • Maths tutor

3405 Views

How do you solve simultaneous equations?

The easiest way to solve simultaneous equations is by elimination. This is the idea of cancelling out one of your variables, the X or Y so that you can solve the remaining variable and then substitute thi...

Answered by Ben H. • Maths tutor

3717 Views

Expand (x+4)(x+3).

To answer this you multiply everything in the left bracket by everything in the right bracket, so rewrite the equation as x(x+3)+4(x+3). Then you can expand each more easily:

x(x+3) = x

Answered by Elliot D. • Maths tutor

30521 Views

How do I remember the trigonometry identities from C3 in the exam?

I often find it difficult to remember all the different identities, so what is useful is instead to just remember the familiar identity sin^2(x) + cos^2(x) = 1 that we have come across many times, and div...

Answered by Joshua S. • Maths tutor

4498 Views