Mathematics
Evaluate:
(2x - 5y) (2x + 3y) for x = 2 and y = 3.
Algebraic Expressions
1 Like
Answer
(2x - 5y) (2x + 3y)
= 2x (2x + 3y) - 5y (2x + 3y)
= 4x(1+1) + 6xy - 10xy - 15y(1+1)
= 4x2 + (6xy - 10xy) - 15y2
= 4x2 - 4xy - 15y2
For x = 2, y = 3
4 x 22 - 4 x 2 x 3 - 15 x 32
= 4 x 4 - 4 x 2 x 3 - 15 x 9
= 16 - 24 - 135
= - 143
Hence, for x = 2, y = 3, the value (2x - 5y) (2x + 3y) = - 143.
Answered By
1 Like