Question

. What should be taken away from 4xy - 3zx + 4yz - 7 to leave xy - 3y2 + 4zx?
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Answer 1

Let,

The polynomial that should be added be P.

Then according to question,

(xy−3yz+4zx)+P=(4xy−3zx+4yz+7)

⇒P=(4xy−3zx+4yz+7)−(xy−3yz+4zx)

⇒P=4xy−3zx+4yz+7−xy+3yz−4zx

Rearranging and collecting like terms,

⇒P=4xy−xy−3zx−4zx+4yz+3yz+7

⇒P=3xy−7zx+7yz+7

Hence, 3xy−7zx+7yz+7 should be added to get the required result.