SOLUTION: Hi, Please can any one help with the following? Many thanks. Hugh Factorise the following expressions. (i) x^2 − x − 42 (ii) 9m^2 − 81n^2

Question 836155: Hi,
Please can any one help with the following? Many thanks. Hugh
Factorise the following expressions.
(i) x^2 − x − 42
(ii) 9m^2 − 81n^2
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
(ii) is the difference of squares.

(i) Look for factors of 42 which could be arranged as sum or difference to give -1. Obvious choice is 6 and 7, but which signs? For the -42, one be negative and other be positive. For the -x, you want 6-7:

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SOLUTION: Hi, Please can any one help with the following? Many thanks. Hugh Factorise the following expressions. (i) x^2 &#8722; x &#8722; 42 (ii) 9m^2 &#8722; 81n^2

SOLUTION: Hi, Please can any one help with the following? Many thanks. Hugh Factorise the following expressions. (i) x^2 − x − 42 (ii) 9m^2 − 81n^2