I have a test for all this stuff on tuesday, ive got most of it down except theres a few things i cant work out, like this problem: This ones a linear equation, you have to find out what X is i always end up with 1.25 but the answer is 6.25.. I did a similar question and got it right, except it was more straightforward with no brackets and addition instead of subratction Can you help:icon_sad: Thankss Discuss -Algebra -Exams This Problem
Ok, so first you want to get a common denominator to subtract fractions. so multiply the top and bottom of the first fraction by 3/3 and the top and bottom of the second fraction by 2/2. So you get (6x-9/6)-(10x-10/6)=-4. Subtract the numerators to get -4x+1/6=-4. Multiply both sides by 6 to clear the fraction. So now you have -4x+1=-24. Subtract 1 from both sides and you get -4x=-25. Divide by 4 to get x=-25/-4. The negatives cancel and you get 25/4 which is 6.25.
It comes down to simplification. I'd start by multiplying that five on the top of the second fraction through what's in the parenthases. (2x-3)/2 - (5x-5)/3 = -4 I'd then turn the whole left side of the equation into one fraction by multiplying the first fraction by 3/3 and the second fraction by 2/2. That way, you are effectively multiplying each fraction by one, which does not change the equation at all. (3/3)•(2x-3)/2 - (2/2)•(5x-5)/3 =-4 (6x-9)/6 - (10x-10)/6 = -4 We can now combine those two fractions into one fraction. ((6x-9) - (10x-10))/6 = -4 (6x-9-10x+10)/6 = -4 (-4x+1)/6 = -4 We now multiply both sides by six to get rid of the fraction -4x+1 = -24 We no subtract one from both sides... -4x = -25 And divide both sides by -4. x = -25/-4 = 6.25 Here's the math all together so it looks like work you would do on a homework assignment. (2x-3)/2 - 5(x-1)/3 = -4 (2x-3)/2 - (5x-5)/3 = -4 (3/3)•(2x-3)/2 - (2/2)•(5x-5)/3 =-4 (6x-9)/6 - (10x-10)/6 = -4 ((6x-9) - (10x-10))/6 = -4 (6x-9-10x+10)/6 = -4 (-4x+1)/6 = -4 -4x+1 = -24 -4x = -25 x = -25/-4 = 6.25 Edit: Damn! Beaten to it.
wow, i know what I did wrong now, I got -19 out of the -9 minus the -10 forgot that negative a negative means is adding. Thank You!!
When you subtract a negative number, you add it's possitive version, so if you subtract -10, you are adding 10.
Can you show us your solution so we can see where you went wrong. I worked it out and got x = 6.25 Here is my solution.
The first step you should do is multiply everything by 6 to get rid of the fractions... starfish's solution works, but it makes it waaaaaaaaay easier to make mistakes.
If any of you want a fright, my thesis for my CS degree will be based around a computational problem in algebra. Oddly enough, I'm probably a better mathematician than programmer...