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Secondary 1 | Maths
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hi how do i do this qn
222×(-4) • A² = -888 • A² (Ans)
[1-3 + 2-4 + 3-5 + 4-6 + ... + 885-887 + 886-888]
x A^2
pairing every 2 terms ...
there are 886 pairs
total
= [ 886 x (-2) ] x A^2
= -1772 A^2
alternatively, all the terms cancel out except for the 1st, 3rd, 3rd last, and last terms
total
= [1 + 2 - 887 - 888] x A^2
= -1772 A^2
See 1 Answer
[1-3 + 2-4 + 3-5 + 4-6 + ... + 885-887 + 886-888]
x A^2
pairing every 2 terms ...
there are 886 pairs
total
= [ 886 x (-2) ] x A^2
= -1772 A^2
alternatively, all the terms cancel out except for the 1st, 3rd, 3rd last, and last terms
total
= [1 + 2 - 887 - 888] x A^2
= -1772 A^2