# Parametrics - Preliminary (1 Viewer)

#### bhein

##### New Member
Help - i can't get some of the simple parametric stuff to work. prelim i know - sorry
i can do these questions when both coordinates are positive - but when -ve no idea

Questions from mifocus 11.9 - i am trying to use formula sheet where possible of y-0.5(p+q)x+apq=0
Q1 Find the
(i) gradient and
(ii) equation of chord AB on the parabola
(h) x^2 = -16y where A = (-8p, -4p^2) and B = (-8q, -4q^2)
(i) x^2 = -4y where A = (2s, -s^2) and B = (2t, -t^2)

Q2 Find
(i) the gradient of the tangent,
(ii) the gradient of the normal,
(iii) the equation of the tangent and
(iv) the equation of the normal to the curve
for the following questions
(h) x^2 = -8y at the point (4t, -2t^2)
(i) x^2 = -12y at the point (-6m, -3m^2)

3. Find the point of intersection between the
(i) tangents and
(ii) normals to the curve
for
(i) x^2 = -20y at the points
(10h, -5h2) and (10k, -5k2)
(j) x^2 = -12y at the points (-6p, -3p^2) and (-6q, -3q^2)

Getting + and - swaped around - can't get it.
How am i going to get the hard crap if i can't get these.
Does the HSC normally have the -ve coordinate ones like these - or even -ve parabola?

#### HeroWise

##### Active Member
Can you instead send a pic of the pages? Its pre hard to read the block of writing

many thanks

second one