Simplify (x3 + 3x2 + 5x – 4) – (3x3 – 8x2 – 5x + 6)
The first thing I have to do is take that "minus" sign through the parentheses containing the second polynomial. Some students find it helpful to put a "1" in front of the parentheses, to help them keep track of the minus sign.
Here's what the subtraction looks like, when working horizontally:
(x3 + 3x2 + 5x – 4) – (3x3 – 8x2 – 5x + 6)
(x3 + 3x2 + 5x – 4) – 1(3x3 – 8x2 – 5x + 6)
(x3 + 3x2 + 5x – 4) – 1(3x3) – 1 (–8x2) – 1(–5x) – 1(6)
x3 + 3x2 + 5x – 4 – 3x3 + 8x2 + 5x – 6
x3 – 3x3 + 3x2 + 8x2 + 5x + 5x – 4 – 6
–2x3 + 11x2 + 10x –10
And here's what the subtraction looks like, when going vertically:
x
3
−(3x
3
+3x
2
−8x
2
+5x
−5x
−4
+6)
In the horizontal addition (above), you may have noticed that running the negative through the parentheses changed the sign on each and every term inside those parentheses. The shortcut when working vertically is to not bother writing in the subtaction sign or the parentheses; instead, write the second polynomial in the second row, and then just flip all the signs in that row, "plus" to "minus" and "minus" to "plus".
\
x
3
–3x
3
−2x
3
+3x
2
+8x
2
+11x
2
+5x
+5x
+10x
−4
–6
−10
Either way, I get the answer:
–2x3 + 11x2 + 10x – 10
<span>Jeff Company issues a promissory note to David Company to get extended time on an account payable. David records this transaction by debiting </span>
79-y=2y+22
Add y on both sides
79=3y+22
Subtract 22 from both sides
57=3y
Divide by 3 on both sides
19=y
Answer:
4 
km
Step-by-step explanation:
To find how much farther Hallie biked after lunch compared to the amount she biked before lunch, we can subtract the amounts:
6 
However, we can only subtract fractions that have the same denominator, so we need to convert 
to a fraction with a denominator of 8:
Now, we can't subtract 2 from 8, so we need to 'borrow' from the 6 to make the fraction larger:
Now subtract: 
