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(x - y + 3)(x + y - 7)

Step-by-step explanation:

x^2 - 4x - 21 + 10y - y^2

= x^2 - y^2 - 4x -21 + 10y

= (x - y)(x + y) - 4x + 10y - 21     Now -21 = + 3 * -7   and +3x - 7x =- 4x so we try:

= (x - y + 3)(x + y - 7)

- this expands to the original expression.

26

step-by-step explanation:

step-by-step explanation:

given that there are two triangles j'k'l' and jkl>

the former is got by dilating the second one.

when drawn on a grid, (graph paper) coordinates of vertices of first triangle is

(6,12)j, (9,6)k and (12,9)l

side jk has length = distance between j and k

=

side j'k'=distance between j' and k'

=

ie j'k'l' has sides 1/3 of that of corresponding sides of jkl.

hence scale factor of 1/3 is used to get j'k'l'from jkl