checking my answer

[Sissy Devane]

(5x^2 - 5xy +y^2)+(-9x^2 - 5xy - y^2)+(x^2 + xy -4y^2)
remove the parentheses keeping the same signs
my calculations are;
(5-9+1)x^2 = -3x^2
(1-1-4)y^2 = -4y^2
(-5xy-5xy + xy)= -24xy

answer I have is -3x^2 - 4y^2 - 24xy

 

[wjm11]

(5x^2 - 5xy +y^2)+(-9x^2 - 5xy - y^2)+(x^2 + xy -4y^2)
remove the parentheses keeping the same signs
my calculations are;
(5-9+1)x^2 = -3x^2
(1-1-4)y^2 = -4y^2
(-5xy-5xy + xy)= -24xy

answer I have is -3x^2 - 4y^2 - 24xy

-24xy is not correct.
-5-5+1 = ?

 

[Sissy Devane]

-3x^2-4y^2-9xy

 

[hongsgirl]

Hi Sissy Devane

That's right