Question

Que valores anulam os denominadores nas equações a seguir?
a)7/x+4x/5=3/4x
b)1/x-3=3/x +2
c)1/x²-25=3/2x

Preciso pra hoje!Me ajudem!

Answer 1

$a)\\ \\ \frac{7}{x} +\frac{4x}{5} =\frac{3}{4x} \\ \\ m.m.c.~de~x,~5~e~4x~|~2\\~~~~~~~~~~~~~~~x~~5~~~~2x~|~2\\~~~~~~~~~~~~~~~x~~5~~~~~x~|~5\\~~~~~~~~~~~~~~~x~~1~~~~~x~|~x\\~~~~~~~~~~~~~~~1~~1~~~~~1\\ \\m.m.c.=2.2.5.x=20x\\\\\frac{140+16x^{2}=15}{20x} \\ \\ despreze~o~denominador\\ \\ 16x^{2} =15-140\\ \\ 16x^{2} =-125\\ \\ x^{2} =-\frac{125}{16} \\ \\ x=\sqrt{-\frac{125}{16}}\\ \\ Raiz~nao~existe~em~R~[\sqrt{(-)} ]$

$b)\\ \\ \frac{1}{x-3} =\frac{3}{x+2} \\ \\ m.m.c.=(x-3)(x+2)\\ \\ \frac{x+2=3(x-3)}{(x-3)(x+2)}\\ \\ despreze~o~denominador\\ \\ x+2=3x-9\\ \\ 3x-x=2+9\\ \\ 2x=11\\ \\x=\frac{11}{2}~~ou~~5,5$

$c)\\ \\ \frac{1}{x^{2}-25} =\frac{3}{2x} \\ \\ m.m.c=2x(x^{2} -25)\\ \\ \frac{2x=3(x^{2}-25)}{2x(x^{2}-25)} \\ \\ despreze~o~denominador\\ \\ 2x=3x^{2} -75\\ \\ 3x^{2} -2x-75=0$