Which expression is equivalent to (x^2-3x)(4x^2+2x-9)

For # 3 and 5 you need to use the quadratic formula: 
(-b +/- srt(b^2 - 4ac))/2a 
a, b, and c are representative of this formula: ax^2 +bx + c 

1) 2x^2+3x-9=0 
(2x - 3)(x + 3) = 0 
2x - 3 = 0, x + 3 = 0 
+3 +3, -3 -3 
2x = 3, ***x = -3*** 
/2 /2 
***x = 3/2*** 

2) 5x^2+2x=0 
(x)(5x + 2) = 0 
5x +2 = 0, ***x = 0*** 
-2 -2 
5x = -2 
/5 /5 
***x = -2/5*** 
4) 4x^2+7x-2=0 
(4x - 1)(x + 2) = 0 
4x - 1 = 0, x + 2 = 0 
+1 +1, -2 -2 
4x = 1, ***x = -2*** 
/4 /4 
***x = 1/4***

Yo no me sé esa mala mia

The answer to your question is 1/9