Question

Factorise 18a^2 +84 ab +98 b ^2
Please tell the answer .
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Answer 1

Answer:

(18 • (a2)) - 84ab) + (2•72b2)

((2•32a2) - 84ab) + (2•72b2

4.1 Pull out like factors :

18a2 - 84ab + 98b2 = 2 • (9a2 - 42ab + 49b2) 4.2 Factoring 9a2 - 42ab + 49b2

Try to factor this multi-variable trinomial using trial and error

Found a factorization : (3a - 7b)•(3a - 7b)

Detecting a perfect square :

4.3 9a2 -42ab +49b2 is a perfect square

It factors into (3a-7b)•(3a-7b)

which is another way of writing (3a-7b)2

How to recognize a perfect square trinomial:

• It has three terms

• Two of its terms are perfect squares themselves

• The remaining term is twice the product of the square roots of the other two terms