3 votes 3 votes A function y= 5x^2+ 10x is defined over an open interval x = (1,2). Atleast at one point in this interval, dy/dx is exactly (A) 20 (B) 25 (C) 30 (D) 35 Calculus calculus engineering-mathematics + – Purple asked Feb 1, 2016 Purple 2.2k views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
5 votes 5 votes Use lagrange mean value thm F'(c)=f(b)-f(a)/b-a F(2)=40 F(1)=15 So there exist point c where derivative is 25 Pooja Palod answered Feb 2, 2016 Pooja Palod comment Share Follow See all 0 reply Please log in or register to add a comment.
3 votes 3 votes dy/dx = 10x + 10 x is in (1,2) i.e. x is NOT 1, NOT 2 but it is inbetween 1 and 2. Put = 1/2 u will get dy/dx = 25 Digvijay Pandey answered Feb 1, 2016 Digvijay Pandey comment Share Follow See all 2 Comments See all 2 2 Comments reply Purple commented Feb 2, 2016 reply Follow Share If it was 'closed interval', then we would consider 1,2 also right? 0 votes 0 votes Prashant. commented Apr 16, 2016 reply Follow Share yup 0 votes 0 votes Please log in or register to add a comment.