Write an equivalent expression in standard form

Question

Factored Form =  

Standard Form = ________

Show your reasoning by creating a 3 by 3 table, or explain each step of your equation (how you found your answer)

Answer 1

(x-4)(x+5)

Use the FOIL method: multiply the 1st terms x(x), then outside terms (5x) then inside terms (-4x) then last terms -4(5) =-20. put them altogether

= x^2 -4x +5x -20 = x^2 +x -20

standard form is ax^2 + bx +c as in when you use the quadratic formula y=-b/2a + or - (1/2a)sqr(b^2-4ac)

in this example a= 1, b=1 and c=-20

you could also do this geometrically, create a rectangle with sides x-4 and x+5

cut it up into 4 sections. Put x-4 as the width, on the top

put x+5 as the length or height on the side

then the total area is divided into x^2 on the top left corner, -20 on the lower right

-4x on the top right, and 5x on the bottom left

add the 4 sections up. they sum to x^2 +x -20