Question

use direct method to evaluate the following products

Answer 1

(y+5)(y-3)
By using (x+a)(x+b)=x^2+(a+b)x+ab
=> x=y, a=5 ,b=-3.
(y+5)(y-3)=y^2+[5+(-3)]y+5×-3
=y^2-2y-15

(b-3)(b-5)
By using (x+a)(x+b)=x^2+(a+b)x+ab
=> x=b, a=-3 ,b=-5.
(b-3)(b-5)=b^2+[(-3)+(-5)]b+(-3)(-5)
=b^2-8b-15

(5a+16)(3a-7)

Answer 2

Answer:

$b^{2} - 8b + 15$

Step-by-step explanation:

(b-3) (b-5)

=$b^{2} - (3+5)b + 15$

$b^{2} - 8b + 15$