Hi, I need help with this problem, I tried every possible way and got 17/5 every time, I even checked Wolfram Alpha and it also says the answer is 17/5, Aops says this answer is wrong, plz show me what I did wrong with my calculations!

icecreamlover Jan 29, 2021

#3**+1 **

Without doing any algebra, I can already tell that your answer of 17/5 cannot possibly be correct. This expression requires multiplication and addition of integers and variables, so it is impossible that the answer would yield a rational number.

Anyway, let's see what the real answer is, shall we?

\((x-4)(x-7) + (3-x)(2+x)\\ x^2-7x-4x+28+6+3x-2x-x^2\\ -10x+34\)

This is as far as we can simplify this expression. Remember that this expression is not an equation. I believe your mistake was that you set this expression equal to 0 and solved.

Guest Jan 29, 2021

#6**0 **

(x – 4)(x – 7) + (3 – x)(2 + x)

(x^{2} – 11x + 28) + (–x^{2} + x +6)

x^{2} – x^{2} – 11x + x + 28 + 6

–10x + 34

simplified this is **2(17 – 5x)**

Nothing in the problem you provided said to set the expression equal to zero and solve for x.

_{.}

Guest Jan 29, 2021

#7**+2 **

note for the future: on aops, "simplify" on equations with variables means "combine like terms then write out the equation in terms of the variable".

I use aops so trust me. I've done like 100 questions on simplifying expressions.

KitSoundwave Jan 29, 2021