What are four new machines that led to improved results in agriculture in the Great Plains?

answer:

Explanation:

drought-resistant seed , contour plowing , crop rotation , disease control... Hope that helps!!!

answer

explanation

the given equation is

we can rewrite this as:

let

then the equation becomes:

the factors of 8 that sum up to -9 are {-1,-8}

we split the middle term with these factors to obtain,

we factor by grouping to obtain:

apply the zero product property to get:

but

d is the right answer