00:01
The given curve is y is equal to x a cube minus 3x plus 5.
00:10
We need to find the equation of tangent at 3 .23 and also we need to find the equation of normal.
00:19
Geometrically, the slope of a tangent, slope of the tangent at a point p is derivative of the curve at that point p.
00:36
So let's find the derivative of this curve.
00:39
So what is d .y by dx? derivative of x cube is 3x squared minus derivative of 3x is 3.
00:46
Now, what is the derivative of this curve at this point 3 comma 23? basically, x value is 3, right? because x coordinate is 3 here.
00:55
X, 0 is 3.
00:57
So let's substitute x0 value here.
01:01
So 3 into x0 is 3 square minus 3.
01:04
So how much? 27 minus 3.
01:06
So 24 is the slope of the tangent.
01:09
So this is the slope of the tangent.
01:12
So tangent is also passing through 3 .23.
01:15
So slope is 24 and the line passes through, the tangent passes through 3 .23.
01:28
So what will be the equation of straight line when you know slope and point, y minus y 1 is equal to m into x minus x1.
01:37
So, the equation of tangent is y minus 23 is equal to 24 into x minus 3.
01:43
So when you simplify this, y minus 23 is equal to 24x minus 24 into 3, 72.
01:50
So you can put it in proper form, 24x minus y and 23 minus 72...