#1**0 **

Solve for x:

-21 x^2 - 11 x + 40 = 0

The left hand side factors into a product with three terms:

-(3 x + 5) (7 x - 8) = 0

Multiply both sides by -1:

(3 x + 5) (7 x - 8) = 0

Split into two equations:

3 x + 5 = 0 or 7 x - 8 = 0

Subtract 5 from both sides:

3 x = -5 or 7 x - 8 = 0

Divide both sides by 3:

x = -5/3 or 7 x - 8 = 0

Add 8 to both sides:

x = -5/3 or 7 x = 8

Divide both sides by 7:

**x = -5/3 or x = 8/7**

Guest Dec 10, 2020