# Factor by grouping: 5c^2-39c-8

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`5c^2-39c-8`

`= 5c^2-40c+c-8`

`= 5c(c-8)+1(c-8)`

`= (c-8)(5c+1)`

** So by grouping **`5c^2-39c-8 = (c-8)(5c+1)`

**Sources:**

`5c^2-39c-8`

Multiply `a xx c` `a=5` `b=-39` `c=-8`

`5xx-8 = -40 ` then find factors of -40 that minus to -39

these numbers will be -40 and 1, plug them into the problem

`5c^2-40c+1c-8` now group the numbers and find the highest number they have in common

`(5c^2-40c)(1c-8)`

`5c(c-8) 1(c-8)`

`(5c+1)(c-8)`