The Student Room Group
Reply 1
(x+2)(x+1)(2x-1)=0
2x^3 + 5x^2 + x - 2 = 0
y' = 6x^2 + 10x + 1

(x=-1)

y' = 6 - 10 + 1
y' = -3

therefore perp. = 1/3

y = 1/3x+c

and we know y = 0

0 = 1/3(-1) + c

c = 1/3

NORMAL: y = 1/3x + 1/3

y' = 6x^2 + 10x + 1
y' = 6 + 10 + 1 = 17

y = 17x + c

y = 2x^3 + 5x^2 + x - 2 = 6

6 = 17 + c

c = -11

TANGENT: y = 17x - 11

so:

17x - 11 = 1/3x + 1/3
16/2/2x = 11/1/3x
x = 0.68

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hah, i even impressed myself :rolleyes:
Reply 2
Thankyou!

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