Answer: (x−7)(x+6)
Step-by-step explanation:
x2 – x – 42
Which two numbers add up to −1 and multiply to −42? Well it's -7 and 6, so the answer is (x−7)(x+6).
To solve this problem you must apply the following proccedure:
1. <span>You have a total of 21 coins, all nickels and dimes. Then:
x:nickels=5 cents
y: dimes=10 cents
x+y=21
2. You have that the total value is $1.70. Then:
5x+10y=170
3. The system of equation is:
x+y=21 (i)
5x+10y=170 (ii)
4. You have:
x+y=21
x=21-y
5(21-y)+10y=170
105-5y+10y=170
y=13 dimes
x+13=21
x=8 nickels</span>