At t mins past 2 pm  the time needed by the minutes hand and a clock to show 3 pm was found to be 3 mins less than t^2/4 mins . Find t
 
Answer is given in solution but i m not able to understand . Explain me with suitable statement .

Asked by sucharitasahoo1 | 24th Nov, 2017, 06:02: PM

Expert Answer:

begin mathsize 16px style Given space time space needed space by space the space minutes space hand space show space 3 pm space is
60 minus straight t space and space it space is space less space than space left parenthesis straight t squared divided by 4 right parenthesis space by space 3
Hence space the space quadratic space equation space becomes comma space
left parenthesis straight t squared divided by 4 right parenthesis space – space 3 space equals space 60 space – space straight t space
fraction numerator left parenthesis straight t squared space – space 12 right parenthesis over denominator 4 end fraction space equals space 60 space – space straight t space
left parenthesis straight t to the power of 2 space end exponent – space 12 right parenthesis space equals space 240 space – space 4 space straight t space
straight t squared space – space 12 space – space 240 space plus space 4 space straight t space equals space 0 space
straight t squared space plus space 4 straight t space – space 252 space equals space 0 space
straight t squared space plus space 18 straight t space – space 14 straight t space – space 252 space equals space 0 space
straight t left parenthesis straight t space plus space 18 right parenthesis space – space 14 left parenthesis straight t space plus space 18 right parenthesis space equals space 0 space
left parenthesis straight t space plus space 18 right parenthesis left parenthesis straight t space – space 14 right parenthesis space equals space 0 space
left parenthesis straight t space plus space 18 right parenthesis space equals space 0 space or space left parenthesis straight t space – space 14 right parenthesis space equals space 0 space
therefore space straight t space equals space minus space 18 space or space straight t space equals space 14 space
Since space straight t space cannot space be space negative comma space straight t space equals space 14 space end style

Answered by Arun | 24th Nov, 2017, 06:40: PM