Need some help with math

[Sonic]

Sorry. Didn't mean for everyone to go through so much trouble. He said the course is "agebra and trig." If there really aren't any clear answers that is ok. It's a college course and it's for some type of engineering. I guess he will need to hit the books for that class.

 

[Xenus]

Oh come on he hasn't even met the fun of calculus yet. Now that has a lot of pain in the ass canceling rules. Is there any use for implict differentiation or is it just another and harder way to differentiate.

 

[akira888]

Sonic:
It's no big deal. I was happy to help. :smile: I was a graduate instructor for a couple of years (Calculus I and II, Linear Algebra) - horrible pay but it was (mostly) wonderful.

Xenus:
Or the fun of graduate level Complex Analysis.

Yes, implicit differentiation is quite important I'm afraid. :smile: Have you taken Calculus of Several Variables yet? (senior undergrad level)

 

[Xenus]

Nope first day off to college. But I took AP Calc. in high school so I atleast know what to expect up to that level. Going bachwards whatgg ever that was called was quite simple but it has been a year so I have to refresh my memory. We stopped just before differential equations in highschool.

 

[Silkworm]

Um, the square of 5 + (3x+2)^0.5 is 25 + 10 * sqrt(3x+2) + (3x+2), not 25 + (3x+2)

(a+b)^2 = a^2 + 2*a*b + b^2
(a+b)^2 != a^2 + b^2

oops, my bad... (hangs head in shame)

=Xenus]sqrt(3 - 3x) * sqrt(3 - 3x) = 3 + ( sqrt(3) * sqrt(3x) ) + ( sqrt(3) * sqrt(3x) ) + 3x

should be

sqrt(3 - 3x) * sqrt(3 - 3x) = 3 + ( sqrt(3) * sqrt(-3x) ) + ( sqrt(3) * sqrt(-3x) ) + 3x

sqrt(3-3x) != sqrt(3) -sqrt(3x), so both are wrong.

Been years since I've had to do any sort of quadratic algebra, the rust is showing. Anyway here's my latest stab at working it out:

sqrt(3-3x) = 5+ sqrt(3x+2)

[squared both sides of the eqn]

(3-3x) = 25 + 2*5*sqrt(3x+2) + (3x+2)

[re-arrange]

10*sqrt(3x+2) = -(6x+24)

[square again]

100*(3x+2) = 36*(x²+8x+16)

[re-arrange]

x² + 8x - (100/12)x + 16 - (100/18) = 0
x² - (1/3)x + (94/9) = 0

eqn is of the form ax²+bx+c, using the quadratic formula
x = -b ± (sqrt(b² - 4*a*c))÷(2*a)

but because (b² - 4*a*c) here gives us a negative result the roots are complex.