Question

(x+5) (x-4)
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Answer 1

(x + 5 )(x - 4) =

x^2 - 4x + 5x - 20 = 0

x^2 + x - 20 = 0




(x + 5) (x - 4) = 0

x + 5 = 0        x - 4 = 0

x = -5             x = 4

(x+ 5)(x - 4) = 0                    (x + 5 )(x-4)= 0

( -5 + 5)(-5 -4) = 0                 (4 + 5)(4 -4)= 0

(0)(-9) = 0                              (9)(0) = 0

0 = 0                                         0 = 0