Toán Lớp 6: Tính
1/1.3+1/3.5+1/5.7+ ..+1/99.101
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Toán Lớp 6: Tính
1/1.3+1/3.5+1/5.7+ ..+1/99.101
Comments ( 2 )
=1/2.(2/1.3+2/3.5+2/5.7+…+2/99.101)
=1/2.(1/1-1/3+1/3-1/5+1/5-1/7+…+1/99-1/101)
=1/2.(1/1-1/101)
=1/2.(101/101-1/101)
=1/2. 100/101
=50/101
=(1.2/1.3+1.2/3.5+1.2/5.7+ ..+1.2/99.101):2
=(2/1.3+2/3.5+2/5.7+ ..+2/99.101). 1/2
=(1-1/3+1/3-1/5+1/5-1/7+…+1/99-1/101). 1/2
=(1-1/101). 1/2
=(101/101-1/101). 1/2
=100/101. 1/2
=50/101