Question

use suitable identity of expand the following​

Answer 1

$(z + 4)(z + 5) \\ z(z + 5) + 4(z + 5)$

$z {}^{2} + 5z + 4(z + 5)$

$z {}^{2} + 5z + 4z + 20$

$z {}^{2} + 9z + 20$

$= z {}^{2} + 9z + 20$

Answer 2

Step-by-step explanation:

we can use (x+a)(x+b)

=x^2+(a+b)x+ab

z^+4+5*z+4*5

=z^2+9z+20