<em>1)y(наим) -будет в вершине:</em>
<em>x(в)=-b/2a=0</em>
<em>y(в)=0^2+3=3</em>
<em>y(наим) =3</em>
<em>2)y(наиб):</em>
<em>1.(<span>√2)^2+3=5</span></em>
<em><span>2.(<span>√3)^2+3=6</span></span></em>
<em><span><span>3.5<6 ,значит :</span></span></em>
<em><span><span>y(наиб)=6</span></span></em>
1)sin390⁰-sin(-420⁰)+ctg(2π+π/4)=
=sin(360⁰+30⁰)-sin(-360⁰-60⁰)+ctgπ/4=
=sin30⁰-(-sin60⁰)+1=sin30⁰+sin60⁰+1=1/2+√3/2+1=(3+√3)/2;
2)2cos30⁰·ctg60⁰-sin3π/2=2·(√3/2)·(√3/3)-(-1)=2·3/6+1=2;
a[1]=7
d=1.5
a[n]=a[1]+(n-1)*d
a[9]=7+8*1.5=19
a[20]=7+19*1.5=35.5
S[n]=(a[1]+a[n])/2 *n
S[9]=(7+19)/2*9=117
S[20]=(7+35.5)/2*20=425
сумму членов прогрессии с 10 до 20 члена включительно равна
S[20]-S[9]=425-117=308
ответ: 308
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1.S2=b1(q-1)/q-1,
b4=b1*q^3
b1=b4/q^3=1/27*(3)^3=1/3
S2=b1(q-1)/q-1=1/3*1/1=1/3.