the quadratic function (1 Viewer)

[jnney]

find the gradients of the tangents to y=2+5x-3x^2 which pass through the point (1,7)

 

[Alkanes]

dy/dx = 5 - 6x
= 5 - 6(1)
= -1??

 

[powlmao]

When x=1


Sub in

y+x-8=0

Whoops, found the equation of the tangent.

 

[jnney]

The answer is -7 and 5.

And by the way, you can't just differentiate it and sub x = 1 in , because that coordinate doesn't like on the curve.

 

[powlmao]

The answer is -7 and 5.

And by the way, you can't just differentiate it and sub x = 1 in , because that coordinate doesn't like on the curve.

Argh, i messed up and clicked the wrong buttom

 

[Alkanes]

I knew something was suss haha

 

[powlmao]

Besides the number typo I have the method right?

 

[elbatiolpxeho]

The general equation of any line through (1,7) is:



Sub into other function:



If the line is a tangent then the discriminant is equal to zero.



Solve for m then go fuck bitches mmmkay.

 

[SpiralFlex]

When x=1


Sub in

y+x-8=0

Whoops, found the equation of the tangent.

You are differentiating with respect to . So it should be As the title suggest you would involve the use of discriminants.