C= 2.3+3.4+4.5+………..+60.61
giải chi tiết nhé
C= 2.3+3.4+4.5+………..+60.61 giải chi tiết nhé
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C= 2.3+3.4+4.5+………..+60.61
giải chi tiết nhé
Edana Edana
$C= 2.3+3.4+4.5+………..+60.61^{}$
$3C=2.3.4+3.4.4+4.5.4+………..+60.61.4^{}$
$3C=2.3.(4-0)+3.4.(5-1)+4.5.(6-2)+………..+60.61.(62-58)^{}$
$3C=2.3.4+3.4.5-1.2.3+4.5.6-2.3.4+………..-58.59.60+60.61.62-58.59.60^{}$
$3C=60.61.62^{}$
$3C=226920^{}$
$C=226920÷3^{}$
$⇒C=75640^{}$
Nho
`C=2.3+3.4+4.5+…..+60.61`
`=>3C=2.3.3+3.4.3+4.5.3+…+60.61.3`
`=>3C=2.3.(4-1)+3.4.(5-2)+4.5.(6-3)+…+60.61.(62-59)`
`=>3C=2.3.4-1.2.3+3.4.5-2.3.4+4.5.6-3.4.5+…+60.61.62-59.60.61`
`=>3C=60.61.62-1.2.3`
`=>3C=226920-6`
`=>3C=226914`
`=>C={226914}/3`
`=>C=75638`