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secondary 2 | Maths
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Please explain how to use the box method thanks
Date Posted: 5 years ago
Views: 247
Basically a guess and check.
Write the term in x² in the upper left box first. Write the constant term in the lower right box next.
For example , your question 13.
x² + 9x - 36. So write x² in the upper left box first, write -36 in the lower right box next.
Now you need to guess and check the factors of the terms you wrote in the boxes.
x² = x × x (only possible combination)
36 = -6 x 6 or 6 x -6
36 = -4 x 9 or 4 x -9
36 = -3 x 12 or 3 x -12
36 = -2 x 18 or 2 x -18
36 = -36 x 1 or 36 x -1
you need to find which combination of factors will give you +9x for the sum of the two remaining boxes.
You will realise that in this case, only the -3 x 12 combination will give the +9x.
Because x × -3 = -3x
x × 12 = 12x
12x - 3x = 9x
Write the term in x² in the upper left box first. Write the constant term in the lower right box next.
For example , your question 13.
x² + 9x - 36. So write x² in the upper left box first, write -36 in the lower right box next.
Now you need to guess and check the factors of the terms you wrote in the boxes.
x² = x × x (only possible combination)
36 = -6 x 6 or 6 x -6
36 = -4 x 9 or 4 x -9
36 = -3 x 12 or 3 x -12
36 = -2 x 18 or 2 x -18
36 = -36 x 1 or 36 x -1
you need to find which combination of factors will give you +9x for the sum of the two remaining boxes.
You will realise that in this case, only the -3 x 12 combination will give the +9x.
Because x × -3 = -3x
x × 12 = 12x
12x - 3x = 9x
See 1 Answer
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I hope this helps you! :)
Date Posted:
5 years ago
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