Question

The sum of two expressions is (x2

+9x-13). If one of them is (2x2

-5x+7).Find the other.​

Answer 1

Step-by-step explanation:

m = 9x2 – 4xy + 5y2

n = 3x2 + 2xy – y2

(i) 2m – n = 2(9x2 – 4xy + 5y2) – (-3x2 + 2xy – y2)

= 18x2 – 8xy + 10y2 + 3x2 – 2xy + y2

= 18x2 + 3x2 – 8xy – 2xy + 10y2 + y2

= 21x2 – 10xy + 11y2

(ii) m + 2n = (9x2 – 4xy + 5y2) + 2(-3x2 + 2xy – y2)

= 9x2 – 4xy + 5y2 – 6x2 + 4xy – 2y2

9x2 – 6x2 – 4xy + 4xy + 5y2 – 2y2

= 3x2 + 3y2

(iii) m = 9x2 – 4xy +5y2

n = -3x2 + 2xy – y2

Now, m – 3n = 9x2 – 4xy + 5y2 – 3(-3x2 + 2xy – y2)

= 9x2 – 4xy + 5y2 + 9x2 – 6xy + 3y2

= 18x2 – 10xy + 8y2

Answer 2

Answer:

x^2+4x-20

Step-by-step explanation:

2x^2-5x+7 + other expression = x^2+9x-13

so:

x^2+9x-13-2x^2-5x+7=other expression

=x^2+4x-20

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