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43 votes
43 votes
Factorise the following.​

Factorise the following.​-example-1
User Leonardo Cavalcante
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1 Answer

9 votes
9 votes

Answer:

x²(9x– 11)(9x + 11)

Explanation:

81x⁴ – 121x²

The expression can be factorised as follow:

81x⁴ – 121x²

x² is common to both term. Thus:

81x⁴ – 121x² = x²(81x² – 121)

Recall:

81 = 9²

121 = 11²

Therefore,

x²(81x² – 121) = x²(9²x² – 11²)

= x²[(9x)² – 11²]

Difference of two squares

x²(9x– 11)(9x + 11)

Therefore,

81x⁴ – 121x² = x²(9x– 11)(9x + 11)

User Kober
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