Derive the following with respect to x1: y=(x1*x2)/(x1+x2).

y is a function of x1 and x2. We are asked to derive y with respect to x1, meaning that x2 remains constant. 

Note that y' is the derivative of y.

Both the numerator and denominator of the fraction contain x1. Therefore, we will need to follow the quotient rule of differentiation.

dy/dx1=[ (x1*x2)' *(x1+x2) - (x1x2)(x1+x2)' ] / [(x1+x2)2] ,   

dy/dx1=[x2*(x1+x2)-(x1*x2*1)]/  [(x1+x2)2],

Therefore: dy/dx1=x2/(x1+x2)  -  x1*x2/(x1+x2)2

TK

Related Maths A Level answers

All answers ▸

integrate by parts ln(x)/x^3


How do you complete the square?


The function f is defined for all real values of x as f(x) = c + 8x - x^2, where c is a constant. Given that the range of f is f(x) <= 19, find the value of c. Given instead that ff(2) = 8, find the possible values of c.


The variables x and y are related by y = 5^x. How do I find the value of x when y is set to 15?