Factor the following polynomial completely. -0.8x2 - 6.4x + 7.2

-0.8(x + 9)(x - 1)

Step-by-step explanation:

Note that 0.8 is a factor of the three coefficients -0.8, -6.4 and 7.2.  Thus,

-0.8x2 - 6.4x + 7.2  =  0.8(-1x^2 - 8x + 9), or, equivalently,

                               = -0.8(x^2 + 8x - 9), which factors further as follows:

                                = -0.8(x + 9)(x - 1)