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Во, изи,пиши в лсроопегтпгтсор
<span><span><span>(<span>a+b</span>)</span><span>(<span><span><span>a 2</span>−<span>ab</span></span>+<span>b 2</span></span>)</span></span>= <span><span>a^3</span>+<span>b^3</span></span> </span><span>. </span>
A1=3 d=3
an=a1+(n-1)d
an=3+3(n-1)
3+3(n-1)≤300
3(n-1)≤297
n-1≤99
n≤100
Sn=(2a1+(n-1)d)*n/2
S100=(6+297)*100/2=300*50=1500
Решение а) и г), как для примера во вложении.