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The mean of 5 numbers is 42. The 5 numbers are 45,29,63,42 and X. Find the value of X.

42 x 5 = 210.

45+29+63+42 = 179.

210 - 179 = 31

X = 31

JF
Answered by Joseph F. Maths tutor
4879 Views

Express 3x^2+18x-1 in the form a(x+b)^2 +c

3x^2+18x-1 Bracket out 3x^2+18x  Factorise by bringing out the common factor of 3 = 3(x^2+6x) Divide the x coefficient by 2  =  3(x^2+3x) And then remove the square on the x^2 variable and add a square to...

CO
Answered by Chukwudi O. Maths tutor
13984 Views

Find the x-values of the turning points on the graph, y=(3-x)(x^2-2)

The minimum point occurs where dy/dx=0

We have 2 options: 1.) Expanding the brackets 2.) The product rule of differentiation

The shortest is the product rule: dy/dx= (d/dx)(3-x).(x2

ZE
Answered by Zita E. Maths tutor
3216 Views

The height (h) of water flowing out of a tank decreases at a rate proportional to the square root of the height of water still in the tank. If h=9 at t=0 and h=4 at t=5, what is the water’s height at t=15? What is the physical interpretation of this?

Note: time, t, is measured in minutes, and height, h, is measured in metres.

Let k>0, a constant. 

The differential equation to be solved is given by: dh/dt = - k(h)^0.5.

Us...

SN
Answered by Sandie N. Maths tutor
5341 Views

curve C with parametric equations x = 4 tan(t), y=5*3^(1/2)*sin(2t). Point P lies on C with coordinates (4*3^(1/2), 15/2). Find the exact value of dy/dx at the point P.

dy/dx = dy/dt *dt/dx (chain rule).

x=4tan(t) hence dx/dt = 4 sec2(t)

y = 531/2sin(2t) hence y'= 1031/2 cos(2t)

therefore dy/dx = 103...

HP
Answered by Harry P. Maths tutor
8040 Views

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