Héctor
A little attempt to write Maths in English (I know it is not a common topic when you learn a language, but I'm studying Physics, so it's important for me to know how to write Maths propperly in English. I would like to know if the text sounds natural as if it would be real) ///////////////// In the next short article we will try to show how to get the expression for the roots of a second-order linear equation using squares of first-order polynomials whose roots will be the roots of the second-order linear equation: a*x^2 + b*x + c = 0 (I) To avoid any kind of misunderstanding is needed to explain what some expressions mean: - 'alpha*beta' symbol means alpha times beta - 'alpha/beta' means alpha divided by beta - 'alpha^(beta)' means raise the number or expression alpha to the power of beta, which could be a number or an algebraic expression - 'sqrt(alpha)' means the square root of alpha. Let be 'x_1' and 'x_2' the two roots of the equation (I) whose variable is 'x'. We are trying to write the previous equation as perfect square of two first-order polynomials with roots 'x_1' and 'x_2': (x-x_1)*(x-x_2) = 0 (II) Now, we will multiply both sides of (I) by '4*a': 4*(a^2)*(x^2) + 4*a*b*x + 4*a*c = 0 (III) Adding to both sides of (IV) 'b^2' we got: 4*(a^2)*(x^2) + 4*a*b*x + 4*a*c + b^2 = b^2 (IV) Moving '4*a*c' to the right side we have: 4*(a^2)*(x^2) + 4*a*b*x + b^2 = b^2 - 4*a*c (V) Now, if we remember that a perfect square is: (alpha + beta)^2 = alpha^2 + 2*alpha*beta + beta^2 (VI) we see that the left side of (VI) is already a perfect square, so we can write (VI) as follows: (2*a*x + b)^2 = b^2 - 4*a*c (VII) Taking the square root to both sides of (VIII) we have two options: 2*a*x_1 + b = sqrt(b^2 - 4*a*c) => x_1 = (-b + sqrt(b^2 - 4*a*c))/(2*a) (VIII) 2*a*x_1 + b = - sqrt(b^2 - 4*a*c) => x_2 = (-b - sqrt(b^2 - 4*a*c))/(2*a) (IX) And the problem is resolved, because we have already obtained the expression we were looking for.
Jul 29, 2015 6:29 PM
Corrections · 7
1

A little attempt to write Maths in English

(I know it is not a common topic when you learn a language, but I'm studying physics, so it's important for me to know how to write about maths properly in English. I would like to know if the text sounds natural as if it would be was real)

/////////////////

In the next short article we will try to show how to get the expression for the root [singular] of a second-order linear equation using squares of first-order polynomials whose roots will be the roots of the second-order linear equation:

a*x^2 + b*x + c = 0 (I)

To avoid any kind of misunderstanding is we needed to explain what some of these expressions mean:
- 'alpha*beta' symbol means alpha times beta
- 'alpha/beta' means alpha divided by beta
- 'alpha^(beta)' means raise the number or expression of alpha to the power of beta, which could be a number or an algebraic expression
- 'sqrt(alpha)' means the square root of alpha.

Let be 'x_1' and 'x_2' be the two roots of the equation (I) whose variable is 'x'. We are trying to write the previous equation as the perfect square of the two first-order polynomials with roots 'x_1' and 'x_2':

(x-x_1)*(x-x_2) = 0 (II)

Now, we will multiply both sides of (I) by '4*a':

4*(a^2)*(x^2) + 4*a*b*x + 4*a*c = 0 (III)

Adding to both sides of (IV) 'b^2' we get: [the reader is in the present tense] 

4*(a^2)*(x^2) + 4*a*b*x + 4*a*c + b^2 = b^2 (IV)

Moving '4*a*c' to the right side we have:

4*(a^2)*(x^2) + 4*a*b*x + b^2 = b^2 - 4*a*c (V)

Now, if we remember that a perfect square is:

(alpha + beta)^2 = alpha^2 + 2*alpha*beta + beta^2 (VI)

we see that the left side of (VI) is already a perfect square, so we can write (VI) as follows:

(2*a*x + b)^2 = b^2 - 4*a*c (VII)

Taking the square root to both sides of (VIII) we have two options:

2*a*x_1 + b = sqrt(b^2 - 4*a*c) => x_1 = (-b + sqrt(b^2 - 4*a*c))/(2*a) (VIII)
2*a*x_1 + b = - sqrt(b^2 - 4*a*c) => x_2 = (-b - sqrt(b^2 - 4*a*c))/(2*a) (IX)

And the problem is resolved [we can also just say "solved"], because we have already obtained the expression we were looking for.

July 29, 2015
I am glad I could help Hector. Wish you the best with your studies mate.
July 31, 2015
Hi Karl, Yes, you're right. I was writing a draft and I forgot to check if all the equation numbers were right, it was a silly mistake, but thanks for telling me about it and the rest of mistakes I've had. And also yes about the last two equations. I was trying to say that after taking the square root of both sides of equation (VII) we got two solutions for 'x', which turns out to be the 'x_1' and 'x_2' I was looking for. Thank you for all :)
July 31, 2015
"Taking the square root to both sides of (VIII) we have two options:" However VIIII does not exist yet. VII does. So you actually operate on VII and not VIII. VIII is generated as well as IX. In addition, it should be "taking the square root of both sides" instead of to both sides. Also how do you go in VII -> VIII from x to x_1. In addition in IX how does your x_1 become => x_2. Just way to many things going on here. I kind of see what you are trying to do here trying to say that x_1 and x_2 are your two solutions but I am not sure is presented in a proper mathematical way. Anyway good luck with all this. Message me any time if you want to talk about it. Maybe I am just confused :) .
July 30, 2015
Adding to both sides of (IV) 'b^2' we get. You can not add to both sides of (IV) when you do not have the IV yet. It should be Adding to both sides of (III) 'b^2' we get. (and basically you get IV). There might be other issues but I need to think about it. You need to get some solid English Math books mate (if you do not already have any). "Math speech" in English no small matter.
July 29, 2015
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