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Hello people ~
factorise:21x²-43x-14​

User Arvidj
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1 Answer

24 votes
24 votes

Answer:


\displaystyle [7x + 2][3x - 7]

Explanation:

Find two quantities that when differed to 43, they also multiply to 294. Those will be 6 and 49. The TINIER quantity gets the plus symbol because the B-value is −43, therefore 49 gets the minus symbol, leaving 6 with the plus symbol. In extension, sinse we have a leading coefficient greater than one, we need to take extra procedures. Here is how it is done:


\displaystyle 21x^2 - 43x - 14 \\ \\ [21x^2 + 6x] - [49x - 14] \\ 3x[7x + 2] - 7[7x + 2] \\ \\ \boxed{[7x + 2][3x - 7]}

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User Pankaj Cheema
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