Substitute each entries of the polynomial in the black box :
Multiply the first number of row one and the and the first number of row 2 : x x x = x²
substitute below the x :
Now multiply x by ( -8 ) = -8x
Substitute just below ( - 8)
Similarly multiply 2 first by x and then by ( -8 )
2 x X = 2X
2 x ( -8) = -16
Thus on adding the entries of white block we get along the white line as shown in the figure we get :
Thus, : ( x- 8 )(x + 2) = x² -6x - 16
Answer : ( x- 8 )(x + 2) = x² -6x - 16
