Question

A=3x²-5xy, B=x²-4y²,C=7xy+2y² determine

 

a) A-B+C             B)A-B-C

Answer 1

 

 

A = 3x² - 5xy

B = x² - 4y²

C = 7xy + 2y² 

 

a) A - B + C

 

= (3x² - 5xy) - (x² - 4y²) + (7xy + 2y²)

= 3x2 - 5xy - x^2 + 4y^2 + 7xy + 2y^2

= 2x^2 + 2xy + 6y^2

= 2(x^2 + xy + 3y^2)

 

B) A - B - C

 

= (3x² - 5xy) - (x² - 4y²) - (7xy + 2y²)

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

= 2x^2 - 12xy + 2y^2

= 2(x^2 - 6xy + y^2)