Question

23. If A = 9x2+6xy-9y2 , B= 4y2 -6x2 -7xy and C= -3x2+xy+5y2 , Show that A+B+C =0.

Answer 1

Answer:

$9 {x}^{2} + 6xy - {9y}^{2} + 4 {y}^{2} - {6x}^{2} - 7xy - 3 {x}^{2} + xy + 5 {y}^{2} \\ ({9x}^{2} - {6x}^{2} - {3x}^{2} ) + (6xy - 7xy + xy) + {( - 9y}^{2} + {4y}^{2} + {5y}^{2} ) \\ = 0 + 0 + 0 \\ = 0$

Answer 2

Answer:

A+B+C= (9x2+6xy-9y2)+(4y2 -6x2 -7xy)+(-3x2+xy+5y2)

=(9x2-6x2-3x2)+(6xy-7xy+xy)+(-9y2+4y2+5y2)

=0+0+0

=0