Question 434479
First part	x	mph													
Second Part 	-5	mph													
															
Distance first part	30	miles													
Distance second part	16	miles													
															
speed first part	x mph											
speed second part =	x-5	mph											
Total rowing time 5	hours												
Time first part	30/x											
Time second part 16/(x-5)						
Time first part + time second part =5	hours	
30/x+16	/(x-5)=	5			
LCD =(x	)*(x-5)							
multiply the equation by the LCD															
we get															
30*(x-5	)+16x=5			
30x-150	+16x=5X^2-25x
46x -150=5X^2-25x								
5X^2-71x+150	=0							
5x^2-71x+150=0									
/5														
X^2-14.2x+30=0									
Find the roots of the equation by quadratic formula			
a=	1	b=	-14.2	c=	30				
b^2-4ac=	201.64	-	-120					
b^2-4ac=	81.64	,{{{sqrt(	81.64	)}}}=	9.04		
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}															
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}															
x1=(	14.2	+	9.04	)/	2										
x1=	11.62														
x2=(	14.2	-9.04	) /	2											
x2= 	2.58	This is not possible

Speed first part = 11.62 mph
Speed second part = 6.62 mph