The question:
y=3.48x^2, determine the positionson the curve (x,y) of the left most tangent and the right most tangent that pass through the point (-5.67, -44.75).
If there is no tangent for either the left or right, just say none.
Round to 4 dec. places.
Thanks
Find the most left and right tangent
y=a∗x2a=3.48Point (xp,yp) : (xp=−5.67 , yp=−44.75)Find the tanget Point (xt,yt)yt=a∗x2tSlop of y=a∗x2 is y′=2a∗xtSlop of the line through Point p is y′=yt−ypxt−xpthe slops must be equal: y′=2a∗xt=yt−ypxt−xp⇒2a∗xt∗(xt−xp)=yt−yp|yt=a∗x2t2a∗xt∗(xt−xp)=a∗x2t−yp2a∗x2t−2a∗xt∗xp=a∗x2t−yp2a∗x2t−a∗x2t−2a∗xt∗xp+yp=0a∗x2t−2a∗xt∗xp+yp=0
⇒xt1,2=xp±√x2p−ypayt1,2=a∗x2t1,2
xt1=−5.67+√(−5.67)2−(−44.753.48)xt1=−5.67+6.70880730103=1.03880730103yt1=3.48∗1.038807301032=3.75533971815right most tangent
xt2=−5.67−√(−5.67)2−(−44.753.48)xt2=−5.67−6.70880730103=−12.3788073010yt2=3.48∗(−12.3788073010)2=533.257348282 left most tangent
This one is a little tough!!
The slope of a tangent line to the given parabola at any point is just y' = 6.96x
Now, what we're looking for is at least one point on the parabola where the line through (-5.67, - 44.75) is tangent to that point (or points).
Let's call the point(s) on the parabola (x, 3.48x^2). And the slope of the tangent line at that point is just 6.96x.
So, using this point on the parabola and the point (-5.67 , - 44.75), we have that, using the slope "formula,"
(3.48x^2 + 44.75) / (x + 5.67) = 6.96x
(3.48x^2 + 44.75) /(x + 5.67) - 6.96x = 0
And solving this equation using the onsite calculator, we have....
(3.48×x2+44.75)(x+5.67)−6.96×x=0⇒{x=−(√3406662741+49329)8700x=(√3406662741−49329)8700}⇒{x=−12.378807301025932x=1.038807301025932}
And the equation of the line that goes through (-5.67, -44.75) and touches the parabola at 1.038807301025932 is given by
y +44.75 = 6.96(1.038807301025932)(x + 5.67)
y = 7.23009881514048672x + 40.9946602818465597024 - 44.75
y = 7.23009881514048672x -3.7553397181534402976 ........ and rounding, we have
y = 7.23x - 3.755
And the equation of the line that touches the graph at - 12.378807301025932 is given by
y + 44.75 = 6.96( - 12.378807301025932)(x + 5.67)
y = -86.15649881514048672x -488.5073482818465597024 - 44.75
y = -86.15649881514048672x - 533.2573482818465597024 .....and rounding, we have
y = -86.156x - 533.257
A graph of the solution is found here.........https://www.desmos.com/calculator/zoxdwcc43a
Whew!!! That one was pretty challenging!!!
Find the most left and right tangent
y=a∗x2a=3.48Point (xp,yp) : (xp=−5.67 , yp=−44.75)Find the tanget Point (xt,yt)yt=a∗x2tSlop of y=a∗x2 is y′=2a∗xtSlop of the line through Point p is y′=yt−ypxt−xpthe slops must be equal: y′=2a∗xt=yt−ypxt−xp⇒2a∗xt∗(xt−xp)=yt−yp|yt=a∗x2t2a∗xt∗(xt−xp)=a∗x2t−yp2a∗x2t−2a∗xt∗xp=a∗x2t−yp2a∗x2t−a∗x2t−2a∗xt∗xp+yp=0a∗x2t−2a∗xt∗xp+yp=0
⇒xt1,2=xp±√x2p−ypayt1,2=a∗x2t1,2
xt1=−5.67+√(−5.67)2−(−44.753.48)xt1=−5.67+6.70880730103=1.03880730103yt1=3.48∗1.038807301032=3.75533971815right most tangent
xt2=−5.67−√(−5.67)2−(−44.753.48)xt2=−5.67−6.70880730103=−12.3788073010yt2=3.48∗(−12.3788073010)2=533.257348282 left most tangent