Question

find the prouduct using suitable identity (z^2-5) (z^2+8)​

Answer 1

Step-by-step explanation:

(x-a)(x+b)= x^{2} +bx-ax-ab (this is the identity we can use here)

$(x-a)(x+b)= x^{2} +bx-ax-ab\\\\(z^{2}-5)(z^{2}+8) = (z^{2})^{2} +8(z^{2})-5(z^{2})-(5)(8)\\(z^{2}-5)(z^{2}+8) = z^{4}+8z^{2}-5z^{2}-40\\(z^{2}-5)(z^{2}+8) = z^{4}+3z^{2}-40$

= z^{4}+3z^{2}-40

                              Hope it helps you..!