by RStars
 P: 7 Hey, I was going through some mechanics notes and came across this quadratic equation to solve for x. In my notes it is supposed to equal 3 however I do not get that result. I am not sure if I am simplifying it wrong or what. I am ending up with 2.12 for the positive value. Please let me know if you get 3 or 2.12 so that I know if the error is in my calculations or in my notes. Thanks in advanced.
P: 606
 Quote by RStars Hey, I was going through some mechanics notes and came across this quadratic equation to solve for x. In my notes it is supposed to equal 3 however I do not get that result. I am not sure if I am simplifying it wrong or what. I am ending up with 2.12 for the positive value. Please let me know if you get 3 or 2.12 so that I know if the error is in my calculations or in my notes. Thanks in advanced.

It must be some mistake in your notes: if you put $x=3$ in the given eq., one gets that the LHS is not an integer

whereas the RHS is...

DonAntonio
 Admin P: 21,687 Neither 3 nor 2.12 are roots of the equation as you wrote it.
P: 7

3 is correct if the LHS is amended to contain 144x2 rather than 144 + x2.
 P: 4 um... I haven't done this in a while so forgive me for being simple.... but that's not an equation. if you put x=10 you end up with the equation 122=900, which isn't true. There's been some kind of mistake.
P: 606
 Quote by evilbrent um... I haven't done this in a while so forgive me for being simple.... but that's not an equation. if you put x=10 you end up with the equation 122=900, which isn't true. There's been some kind of mistake.

No, that is too an equation. To solve it means to find out the numerical values of x that when substituted in the equation give

a true equality. What you've shown above is that the numerical value x = 10 is not (one of the) a solution(s) of the equation.

DonAntonio
 P: 4 oh, ok, yes. Sorry engineering maths was a decade ago for me. It's amazing how quickly the knowledge vanishes. I reduced the original equation down to 0=-71.5x^2+900x-2628 and got 0=(x-4.604)*(x-7.984)

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