urgent svp c pour demain !! merci !!

1) AM^2=AD^2+DM^2=4^2+x^2=x^2+16

2) MF^2=FE^2+ME^2=3^2+(3+4-x)^2=9+(7-x)^2=9+49-14x+x^2=x^2-14x+58

3) a) AM=MF ---> AM^2=MF^2
x^2+16=x^2-14x+58
-14x+58=16

b) -14x+58=16
-14x=16-58
-14x=-42
x=42/14
x=3