Turning points of the curve y = (9x^2 +1)/3x+2

Use quotient rule to differentiate:

dy/dx = (18x(3x+2) - 3(9x2+1))/(3x+2)2

set dy/dx=0:

54x+ 36x - 27x- 3 = 0

9x2 + 12x - 1 = 0

solve quadratic to obtain values of x, and then find corresponding values of y by subbing these x values into original equation.

To find if max or min, differentiate formula twice, then sub in values of x. If f''x > 0, then minimum. If f''x < 0, maximum.

Answered by Jacob H. Maths tutor

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