B= 2100-299+298-297+…..+22
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S tran=5*4=20m2
S tuong=(5*3*2)+(4*3*2)+20=74-14(S cua)=60(m2)
Vay ............ la 60 m2
a, 4.(-\(\dfrac{1}{2}\))3 - 2(-\(\dfrac{1}{2}\))2 + 3.(-\(\dfrac{1}{2}\)) + 1
= -\(\dfrac{1}{2}\) - \(\dfrac{1}{2}\) - \(\dfrac{3}{2}\) + 1
= -1 - \(\dfrac{3}{2}\) + 1
= -3/2
S = \(\dfrac{4}{2.4}\) + \(\dfrac{4}{4.6}\) + \(\dfrac{4}{6.8}\) +......+ \(\dfrac{4}{2012.2014}\) + \(\dfrac{4}{2014.2016}\)
S = 2. ( \(\dfrac{2}{2.4}+\dfrac{2}{4.6}+\dfrac{2}{6.8}+.....+\dfrac{2}{2012.2014}+\dfrac{2}{2014.2016}\))
S = 2.( \(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+\dfrac{1}{6}+.....+\dfrac{1}{2014}-\dfrac{1}{2016}\))
S = 2.(\(\dfrac{1}{2}-\dfrac{1}{2016}\))
S = 2. \(\dfrac{1007}{2016}\)
S = \(\dfrac{1007}{1008}\)
\(\dfrac{3}{2}-|x-\dfrac{3}{4}|=\sqrt{\dfrac{9}{16}}\)
⇔ \(\dfrac{3}{2}-|x-\dfrac{3}{4}|=\dfrac{3}{4}\)
⇔ \(|x-\dfrac{3}{4}|=-\dfrac{3}{4}\)
⇔ \(x-\dfrac{3}{4}=-\dfrac{3}{4}\) hoặc \(x-\dfrac{3}{4}=\dfrac{3}{4}\)
⇔ \(x\) \(=0\) ⇔ \(x\) \(=\dfrac{3}{2}\)
Vậy pt có nghiệm : \(x=0\) hoặc \(x=\dfrac{3}{2}\)
B = 2100 - 299 + 298 - 297 + ... + 22
B = ( 2100 + 298 + ... + 22 ) - ( 299 + 297 + ... + 23 )
B = ( 2100 + 299 + 298 + 297 + ... + 23 + 22 ) - 2( 299 + 297 + ... + 23 )
B = ( 2100 + 299 + 298 + 297 + ... + 23 + 22 ) - ( 2100 + 298 + ... +
24 )
B = 299 + 297 + ... + 23 + 22
22B = 2101 + 299 + ... + 25 + 24
4B - B = ( 2101 + 299 + ... + 25 + 24 ) - ( 299 + 297 + ... + 23 + 22 )
3B = 2101 + 24 - 23 - 22
3B = 2101 + 16 - 8 - 4
3B = 2101 + 4
B = \(\dfrac{2^{101}+4}{3}\)