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Ed has 4 cards. There is a number on each card. Three of the numbers are 12, 6 and 15. The mean of the numbers is 10. What is the fourth number?

To find the mean you add all the numbers together and divide by the number of numbers. Call the fourth number x. Then we know that (12+6+15+x)/4 =10. then multiply both sides by 4 to get 12+6+15+x=40 whi...

Answered by Sarah P. Maths tutor
8483 Views

Integrate x/((1-x^2)^0.5) with respect to x

x = sin(u), dx/du = cos(u), dx = cos(u) * du,[x/(1-x^2)^0.5)] * dx = [sin(u)/((1-(sin(u)^2))^0.5] * cos(u) * du = [sin(u)/(cos(u)^2)^0.5] * cos(u) * du = sin(u) * duIntegral of sin(u) * du = -cos(u) = -(...

Answered by Andrew P. Maths tutor
3839 Views

Express 5/[(x-1)(3x+2)] as partial fractions.

5 = a(3x+2) + b(x-1), x = 1, 5 = a(3+2) +b (1-1), 5 = a(5) + b(0), 5 = 5a, a = 1, x = -2/3, 5 = a(-2+2) + b(-(2/3)-1), 5 = a(0) + b(-5/3), 5 = -5b/3, b = -3, Therefore: 5/[(x-1)(3x+2)] = 1/(x-1) -3/(3...

Answered by Andrew P. Maths tutor
7053 Views

Differentiate sin(x)cos(x) with respect to x?

You will have to use the Product Rule. The Product rule: when y=f(x)g(x), then dy/dx=f'(x)g(x)+f(x)g'(x). In this example, f(x)=sin(x) and g(x)=cos(x). Hence f'(x)=cos(x) and g'(x)=-sin(x). Using these an...

Answered by Matthew M. Maths tutor
4181 Views

Factorise fully 6xyz + 24x^2yz + 18xy^3z^2

So we need to find common factors for each term: 6xyz, 24x2yz and 18xy3z2. Let's start with the numbers. Do the numbers 6, 24 and 18 have a common factor? Yes, 6 . If we t...

Answered by Tom L. Maths tutor
2831 Views

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