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BIDMAS doesn't work??

Why is '1 - 0.5 + 0.2 = 0.7'

Aren't we supposed to do addition before subtraction hence making the answer 0.3?
Reply 1
Avatar for ma_long
ma_long
16
It doesn't matter which way you do addition or subtraction, as long as you do it after multiplication and division.
Reply 2
Avatar for ma_long
ma_long
16
(1-0.5) +0.2 = 0.7
1+ (-0.5+2) = 0.7

It makes no difference.
Reply 3
Avatar for Notnek
Notnek
21
Original post by S.H.Rahman
Why is '1 - 0.5 + 0.2 = 0.7'

Aren't we supposed to do addition before subtraction hence making the answer 0.3?

It should be taught like this

B
I
DM
AS

since D/M have equal precendence as do A/S. For some baffling reason it isn't taught like this.

If you have addition and subtraction then you work from left-to-right.
Reply 4
Avatar for S.H.Rahman
S.H.Rahman
OP
15
Original post by Notnek
It should be taught like this

B
I
DM
AS

since D/M have equal precendence as do A/S. For some baffling reason it isn't taught like this.

If you have addition and subtraction then you work from left-to-right.


How would you simplify:

1 - 1/(k+1)^2 + (2(k+1) + 1)/(k+1)^2(k+2)^2

to make

1 - (k + 2)^-1
Reply 5
Avatar for Notnek
Notnek
21
Original post by S.H.Rahman
How would you simplify:

1 - 1/(k+1)^2 + (2(k+1) + 1)/(k+1)^2(k+2)^2

to make

1 - (k + 2)^-1

Is that

1−1(k+1)2+2(k+1)+1(k+1)2(k+1)2\displaystyle 1-\frac{1}{(k+1)^2}+\frac{2(k+1)+1}{(k+1)^2(k+1)^2}

?

If not, please use more brackets to make it clearer.

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