Question

Use the identity (x + a) (x + b) = x’ + (a + b) x + ab to find (2x - 5y) (2x + 3y).​

Answer 1

Answer:

(2x +5y) (2x + 3y)

= (2x)2 + (5y + 3y) (2x) + (5y) (3y)

= 4x2 + 16xy + 15y2

(ii) (2a2 +9) (2a2 + 5)

= (2a2)2 + (9 + 5) (2a2) + (9) (5)

= 4a4 + 28a2 + 45

(vii) (xyz − 4) (xyz − 2)

+ (xyz)2 + [ (-4) + (-2) ] (xyz) + (-4) (-2)

= x2y2z2 - 6xyz + 8