Question

need help!!! use subtraction theorm to write equivalent expressions : 8y-9x

Answer 1

What is the subtraction theorem? I mean, just look at the expression, there isnt anything that can be done. They arent like terms so they cant be subtracted.

Answer 2

just looking*

Answer 3

so what should i put??

Answer 4

I dont know >.< there are a million different things that are equivalent. If i had to take a guess, it would be one of these two:
\[-9x+8y\]All i did here was switch the order.
Or maybe they want:
\[8y+(-9x)\]
Maybe that is the "subtraction theorem"?

That:\[a-b=a+(-b)\]

Answer 5

Whoever is telling you its called the "subtraction theorem", tell them to stop making up fancy names lol <.<

Answer 6

lol its in the algebra 2 book..

Answer 7

Who wrote that book? im gonna send an angry email...

Answer 8

lolol, jk jk.

Answer 9

haha thanks for the help though i dont kno how to do any of these problems at all lol..

Answer 10

\[3\left| x+2 \right| for x=-4\] need help how do u do this!

Answer 11

so the problem is asking what is the value of:
\[3|x+2|\] when x = 4?

Answer 12

X=-4

Answer 13

whoops! my bad, i see it now. ok, so we are going to let x = -4. So everywhere we see an 'x' in the math expression, we change it to -4. that gives:
\[3|x+2| \iff 3|-4+2|\]make sense so far?

Answer 14

yes

Answer 15

ok, so now we have to actually evaluate it. Those vertical bars "|", are called absolute value bars, and we treat them like parenthesis, so we will calculate whatever is inside them first.

So, we just need to find out what -4+2 is.

Answer 16

an thats -2

Answer 17

right :) so now our problem is:
\[3|-4+2| = 3|-2|\]

Next we need to calculate what the absolute value of -2 is. There is a pretty easy rule for getting the absolute value of a number. You just make it positive. If its already positive, leave it alone. Here are some examples:

|-10| = 10, |10| = 10, |-12341234| = 12341234, |-whatever| = whatever

So what would |-2| be?

Answer 18

2

Answer 19

right again. so now we have:
\[3|-2| = 3(2)\] now we just multiply to get our final answer. \[3(2) = 6\]

So, thats the final answer. When x = -4, 3|x+2| = 6

Answer 20

thank you so much! i get it now. so for \[\left| p+q \right|\] for p=21 and q= -9 you do \[\left| 21+-9 \right| or \left| 21-9 \right|\]?