Factor –7x3 + 21x2 + 3x – 9 by grouping. What is the resulting expression? (3 – 7x)(x2 – 3)
(7x – 3)(3 + x2)
(3 – 7x2)(x – 3)
(7x2 – 3)(3 + x)

The answer is the third option

(3–7x²)(x–3)

Step-by-step explanation:

If you apply the distributive property in (3–7x²)(x–3), you obtain:  

3x-9-7x²(x)+21x²

3x-9-7x³+21x²

When you order the expression, you have:  

-7x³+21x²+3x-9

Then, the answer is (3–7x²)(x–3)

for the friend request.

when a figure, such as triangle (xyz) is reflected over the line y = x to create x'y'z' the x-coordinates and y-coordinates of the original image (pre-image) will be reversed for the image. (e.g., (x, y) > (y, x)) this means that the pre-image position of the x- and y-coordinates switch places which in turn provides a mirror like image of the original xyz.  

i notice that when i draw a line segment from x to x', that the points are parallel from each other -- they are exactly across from each other and do not intersect with any other points.  

yes, think i would see the same characteristic if you drew the line segment connecting y with the reflecting line and then y' with the reflecting line because of the essence of reflections. because it is a mirror image, each point was effected the same way which leads me to conclude that they same would apply to y and y'.