Simple calculation of 15 / 16 times 15

Simple calculation of 15 / 16 times 15

15 out of 16 times 15
=15x(1-1/16)
=15-15/16
=14 and 1 / 16

(2x-3) (4x ^ 2 + 6xy + 9) is what this is equal to

The original formula = (2x-3) [(2x) ² + (2x) * 3 + 3 & #178;]
=(2X)^3-3^3
=8X^3-27.

Explore and calculate: 1 / 1 by 3 + 1 / 3 by 5 + 1 / 5 by 7 +... + 1 / 2009 by 2011

1/1x3+1/3x5+1/5x7+···+1/2009x2011
=1/2x(1-1/3+1/3-1/5+1/5-1/7+···+1/2009-1/2011)
=1/2x(1-1/2011)
=1/2x2010/2011
=1005/2011

1 times one in three plus 3 times one in five plus 5 times one in seven plus... 2009 times one in 2011, I'll give you 10 points

One by one by three plus three by one by five plus five by one by seven plus.. 2009 by one by 2011, because one by one by three = 1 / 2 (1-1 / 3) three by one by five = 1 / 2 (1 / 3-1 / 5). 2009 by one by 2011 = 1 / 2 (1 / 2009-1 / 2011), so the original formula is equal to 1 / 2 {(1-1 / 3) + (1 / 3-1 / 5) + (1 / 2009-1 / 2011)} = 1 / 2 (1 / 2009-1 / 2011)

Calculation: 1 times 3 / 1 + 3 times 5 / 1 2007 by 2009 / 1

1/(1*3)+1/(3*5)+.+1/(2007*2009)
=1/2*(1-1/3)+1/2*(1/3-1/5)+.+1/2*(1/2007-1/2009)
=1/2*(1-1/3+1/3-1/5+.+1/2007-1/2009)
=1/2*(1-1/2009)
=1/2*2008/2009
=1004/2009