Tính bằng cách hợp lí: <span class="MathJax_Preview" style="color: inherit;"><span class="MJXp-math" id="MJXp-Span-1"><span class="MJXp-mi MJXp-italic" id="MJXp-Span-2">A</span><span class="MJXp-mo" id="MJXp-Span-3" style="margin-left: 0.333em; margin-right: 0.333em;">=</span><span class="MJXp-mn" id="MJXp-Span-4">100</span><span class="MJXp-mo" id="MJXp-Span-5" style="margin-left: 0.267em; margin-right: 0.267em;">+</span><span class="MJXp-mn" id="MJXp-Span-6">98</span><span class="MJXp-mo" id="MJXp-Span-7" style="margin-left: 0.267em; margin-right: 0.267em;">+</span><span class="MJXp-mn" id="MJXp-Span-8">96</span><span class="MJXp-mo" id="MJXp-Span-9" style="margin-left: 0.267em; margin-right: 0.267em;">+</span><span class="MJXp-mo" id="MJXp-Span-10" style="margin-left: 0em; margin-right: 0.222em;">.</span><span class="MJXp-mo" id="MJXp-Span-11" style="margin-left: 0em; margin-right: 0.222em;">.</span><span class="MJXp-mo" id="MJXp-Span-12" style="margin-left: 0em; margin-right: 0.222em;">.</span><span class="MJXp-mo" id="MJXp-Span-13" style="margin-left: 0.267em; margin-right: 0.267em;">+</span><span class="MJXp-mn" id="MJXp-Span-14">2</span><span class="MJXp-mo" id="MJXp-Span-15" style="margin-left: 0.267em; margin-right: 0.267em;">−</span><span class="MJXp-mn" id="MJXp-Span-16">97</span><span class="MJXp-mo" id="MJXp-Span-17" style="margin-left: 0.267em; margin-right: 0.267em;">−</span><span class="MJXp-mn" id="MJXp-Span-18">95</span><span class="MJXp-mo" id="MJXp-Span-19" style="margin-left: 0.267em; margin-right: 0.267em;">−</span><span class="MJXp-mo" id="MJXp-Span-20" style="margin-left: 0em; margin-right: 0.222em;">.</span><span class="MJXp-mo" id="MJXp-Span-21" style="margin-left: 0em; margin-right: 0.222em;">.</span><span class="MJXp-mo" id="MJXp-Span-22" style="margin-left: 0em; margin-right: 0.222em;">.</span><span class="MJXp-mo" id="MJXp-Span-23" style="margin-left: 0.267em; margin-right: 0.267em;">−</span><span class="MJXp-mn" id="MJXp-Span-24">3</span><span class="MJXp-mo" id="MJXp-Span-25" style="margin-left: 0.267em; margin-right: 0.267em;">−</span><span class="MJXp-mn" id="MJXp-Span-26">1</span></span></span><script type="math/tex" id="MathJax-Element-1">A=100+98+96+...+2-97-95-...-3-1</script> $\begin{align

Tính bằng cách hợp lí: $A=100+98+96+...+2-97-95-...-3-1$ $\begin{align

4.8/5

Tác giả: Thầy Tùng

Đăng ngày: 18 Aug 2022

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Lời giải chi tiết

Câu hỏi:

Tính bằng cách hợp lí: $A=100+98+96+...+2-97-95-...-3-1$

A. 50

Đáp án án đúng là: A

Lời giải chi tiết:

$\begin{align} & A=100+98+...+4+2-99-97-...-3-1 \\ & \ \ \ =\left( 100-99 \right)+\left( 98-97 \right)+...+\left( 4-3 \right)+\left( 2-1 \right) \\ & \ \ \ =1+1+...+1+1 \\ & \ \ \ =50 \\ \end{align}$

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