Find all solutions by factoring.
4v2 - 25v = 21

(4v + 3) and (v - 7)

Step-by-step explanation:

First rewrite 4v2 - 25v = 21 as 4v^2 - 25v - 21.

Let's now analyze -25v and -21.  We need to identify two integers whose product is 21 and whose sum is -25.  

Note that factors of -21 are ±1, ±3, ±7 and ±21.  Factors of 4 (the coefficient of v^2) are ±1, ±2 and ±4.

Check out the following trial factors:   (4v + 3) and (v - 7).  Does this product come out to the given 4v^2 - 25v - 21?  Yes.   So the desired factors of 4v2 - 25v = 21 are (4v + 3) and (v - 7).  Note how (3)(-7) = -21 and how 4(-7) + 3v add up to -25, the coefficient of the v term.

7

step-by-step explanation: