how do you solve 7y3+y2-8y?

Question

i need help

Answer 1

7y³ + y² - 8y

First you can take out a factor of 'y' :

7y³ + y² - 8y = y(7y² + y - 8)

 

Now you need to think about multiplies of 7 and multiplies of 8:

7 = 7×1

8 = 8×1 = 4×2

 

So if you look at these and try out which multiplies work best you can see that we need to use:             7×1       and       8×(-1)

 

So,

y(7y² + y - 8) = y(7y + 8)(y - 1)                     This is the final answer.

 

 

You can check that this is correct by multiplying it out:

y(7y + 8)(y - 1) = y(7y² - 7y + 8y - 8) = y(7y² + y - 8) = 7y³ + y² - 8y   

⇒ which is the original answer