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The Curve C has the equation 2x^2-11+13. The point Q lies on C such that the gradient of the normal to C at Q is -1/9. Find the x-co-ordinate of Q

The first ste here is the find the general equation for the gradient tangential to the curve. This is done by differentiation of the equation to give 4x-11=dy/dx. dy/dx is the gradient. Now we are given the ...
MH
Answered by Matthew H. • Maths tutor
5311 Views

The radius of a circular disc is increasing at a constant rate of 0.003cm/s. Find the rate at which the area is increasing when the radius is 20cm.

The rate at which the area is increasing, dA/dt, can be written with terms we know or can find out easily: dA/dt=dA/dr x dr/dt.Area of a disc, A = (pi)r^2dA/dr=2(pi)rRate of change of radius, dr/dt=0.003cm/s...
HH
Answered by Henry H. • Maths tutor
12479 Views

Factorise 15r+10

Step 1) look at the numbers Both 15 and 10 are factors of 5 step 2 ) look at the letters there is only one letter 'r' after the 15 step 3) there is only one possible thing that can be factorised out therefor...
JL
Answered by Judy L. • Maths tutor
10555 Views

How do I solve a simple simultaneous equation?

Simultaneous equations pop up all the time in maths, science, and engineering, so being able to solve them is really useful. Although they can look a bit daunting at first, the same general rules apply to so...
JM
Answered by Joe M. • Maths tutor
5295 Views

Solve the equation log(1-x) - log(x) = 1 where log() is the logarithmic function, base 10.

From the rules of logarithms, we know that: log(A) - log(B) = log(A/B) and thus: log(1-x) - log(x) = log[(1-x)/x] Therefore from the question, we know: log[(1-x)/x] = 1 If we then take both sides of the equa...
JD
Answered by Joshua D. • Maths tutor
22780 Views