Question

It A=7x^2+5xy-9y^2,B=4x^2+xy+5y^2and c=4y^2-3x^2-6xy then show that A+B+C=0
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Answer 1

Answer:

I suppose the question is

If A =7x²+5xy-9y²

B= '-4x²' +xy+5y²

C= 4y²-3x²-6xy then prove that A+B+C=0

Step-by-step explanation:

It is quite simple , just substitute the values of A ,B and C in the 'to prove'

i.e., LHS= A+B+C

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

Now remove the brackets

= 7x²+5xy-9y²-4x²+xy+5y²+4y²-3x²-6xy

Concentrate on the variables (x,y,xy). We cannot add numbers with different variables. So change the sequence of the equation,

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

=7x²-7x² +6xy-6xy -9y²+9y²

=0+0+0=0

(as +1-1=0 / -1+1=0 )

If the value of B is not '-4x²' +xy+5y² then the question might be wrong.

Answer 2

maybe there is a typing mistake in your question as to obtain answer 0

B= -4x^2+xy+5y^2

given : A=7x^2+5xy-9y^2

B= -4x^2+xy+5y^2

C=4y^2-3x^2-6xy

A+B+C=0

substitute the values

7x^2+5xy-9y^2-4x^2+xy+5y^2+4y^2-3x^2-6xy=0

7x^2-4x^2-3x^2+5xy+xy-6xy+5y^2+4y^2-9y^2=0

0+0+0=0

therefore A+B+C=0