Bonsoir,
Réduire:
a. x/7 +x/3= (x*3+x*7)/(7*3)= 10x/21
b. 4x/7+(2x+1)/3= 3(4x)/(7*3)+ 7(2x+1)/(7*3)= (12x+14x+7)/21
= (26x+7)/21= (26x/21) +(1/3)
c. 4/x +(2x+1)/3= (4*3)/3x+x(2x+1)/3x= (12+2x²+x)/3x= (2x²+x+12)/3x
d. 1/x-1/x²= (x²*1-1*x)/(x*x²)= (x²-x)/x³= (x-1)/x²