<h3>
Answer: x^2+3x-4</h3>
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Explanation:
You can use the FOIL rule to expand out (x+4)(x-1), but here's another way you could do it.
Let y = x+4
This means we replace (x+4) with y to get y(x-1)
Distribute the y term through to get yx-y which can be written as x(y) - 1(y)
After this, replace y with x+4 getting x(x+4)-1(x+4)
Distribute a second time and simplify like so
x(x+4)-1(x+4)
x^2+4x-1x-4
x^2+3x-4
