Posted by Denis Borris on September 23, 2002 at 00:38:34:
In Reply to: Re: i feel dumb posted by Soroban on September 22, 2002 at 23:06:18:
: : For the problem 3x+25/(x+7) -5= 3/x
: I assume it's: (3x+25)/(x+7) - 5 = 3/x
: : i then got x*x+7 as LCD
: : then i got 3x^2+25x-35=3x+7
: How? Multiply EACH TERM by the LCD: x(x+7).
: x(x+7)(3x+25)/(x+7) - 5x(x+7) = x(x+7)3/x
: Do the appropriate cancelling:
: x(3x+25) - 5x(x+7) = 3(x+7)
: If you survive, you should get: x= -3, x = -7/2
In case you find this less confusing (it's the way I do these):
your equation: (3x+25)/(x+7) - 5 = 3/x
do this first: (3x+25)/(x+7) - 3/x = 5 (in other words, rearrange)
now, let a = 3x + 25 and b = x + 7; then:
a/b - 3/x = 5
get the picture?