There is an error in the derivative.
And you put +
i have about 4 problems here all together
my first problem is this question letter H , below is my working out but my answer seems to be wrong so i dont know what im doing wrong.
Find the equation of (i) the tangent and (ii) the normal to the curve.
answer in the back is
i) 17x - y + 27 = 0
ii) x + 17y + 121 = 0
the other 3 problems are
3: x = 1/2
5: x = 1/3/4
in my text book it doesnt really give me examples directly related to this question to solve it so im quite clueless on question 3 , 4 and 5. The other questions in this chapter are primarily based on questions like 4 and 5. So if someone can help me with those questions i'll be able to do the rest.
thx all help is appreciated.
I can tell you very easily the mistake you've made. The quotient rule you're using is wrong. There's meant to be a minus, NOT a plus, in the numerator of the quotient rule formula. Your derivative and hence gradient are wrong for this reason.
And for 3., 4. and 5. you do know that the gradient of a tangent is given by dy/dx, right?
3. Solve for x and for x .....
4. First find the value of m = dy/dx at x = 2.
5. Solve for x.
thanx such a stupid mistake i made, think i got to use to using the product rule in the previous chapter since it has the +.
just need help on the last 3 now.I can tell you very easily the mistake you've made. The quotient rule you're using is wrong. There's meant to be a minus, NOT a plus, in the numerator of the quotient rule formula. Your derivative and hence gradient are wrong for this reason.
Did you understand why you were asked to solve dy/dx=tan(45°) or tan(135°) ? :-)
For the 5th question, also remember that :
The value of the derivate at a point is the slope of the tangent at this point. This is why you compare the value of the derivate with the slope of the line you want to be parallel with the tangent.
I don't know if it's clear enough :s
That's because the question doesn't specify whether you want 45 degrees from the positive direction or 45 degrees from the negative direction (which is the same as 135 degrees from the positive direction).