How do you simplify (−x2−9xy+5y2)−(4x2−2xy−y2)?

2 Answers
M7chael
Oct 11, 2017

−5x2−7xy+6y2

Explanation:

Your problem is the same as:

(1)(−x2−9xy+5y2)+(−1)(4x2−2xy−y2)

First distribute the 1 and −1:

−x2−9xy+5y2−4x2+2xy+y2

Rearrange the terms and show all the coefficients:

−1x2−4x2−9xy+2xy+5y2+1y2

Combine like terms:

−5x2−7xy+6y2

Pallu
Oct 11, 2017

Simplified ⇒−5x2−7xy+6y2

Factorised form ⇒(−5x+3y)(x+2)

Explanation:

(−x2−9xy+5y2)−(4x2−2xy−y2)

First open the parenthesis:

⇒−x2−9xy+5y2−4x2+2xy+y2

Now group the like terms and solve:

⇒−x2−4x2−9xy+2xy+y2+5y2

⇒−5x2−7xy+6y2

⇒−5x2−7xy+6y2

We can further factorise this as :

⇒−5x2−10xy+3xy+6y2

⇒−5x(x+2y)+3y(x+2y)

⇒(−5x+3y)(x+2)

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