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Comment on Rational Sum of Solutions
Sir, after we came up with
Yes, that's true.
Yes, that's true.
Is this something that often
Yes, that approach will work
Yes, that approach will work when the equation is in the form x² + ax + b = 0
In that case, -a = the SUM of the solutions
And b = the PRODUCT of the solutions.
IMPORTANT: This formula works ONLY FOR equations that have actual solutions.
For example, the equation x² + 2x + 20 = 0 has no solutions, so the formula doesn't work (i.e., if the equation has no solutions, we certainly CAN'T say the sum of the solutions is -2.
I'm not a big fan of formulas like this, because the GRE seldom asks for the sum or product of solutions, and because the formula doesn't apply to unsolvable equations.
Cheers,
Brent
Hi Brent,
When we cross multiplied, why did we directly cross multiply, that wouldve resulted in the expression
3x^2-14= 2x^2-11?
Why did we individually took the terms and factorized them with FOIL method?
We must use the F.O.I.L.
We must use the F.O.I.L. method whenever we multiply two binomials.
More here: https://www.greenlighttestprep.com/module/gre-algebra-and-equation-solvi...
So, in this case, When we cross multiply, we get: (3x - 2)(x + 7) = (2x - 1)(x + 11)
Notice that each set of brackets contains a binomial.
As such we must apply the the F.O.I.L. method.
Does that help?
when should we check if the
There are three main
There are three main instances (when it comes to GRE questions)
1) Absolute value equations (more here: https://www.greenlighttestprep.com/module/gre-algebra-and-equation-solvi...)
2) Square root equations (more here: https://www.greenlighttestprep.com/module/gre-algebra-and-equation-solvi...)
3) Equations with variables in the denominator (just to be extra safe)