|a|=3,|b|=√(1+4+9)=√14
|c|²=|a|²+2*|a|*|b|*cosa+|b|²=9+2*3*√14*1/2√14+14=26
|c|=√26
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x²-14x+12+36/(x-7)²≤0
(x-7)²-37+36/(x-7)²≤0
(x-7)²=a,x≠7
a-37+36/a≤0
(a²-37a+36)/a≤0
(a-1)(a-36)/a≤0
a=36 a-1 a=0
_ + _ +
-------------(0)-------------[1]-------------[36]---------------
-a<0⇒(x-7)²<0 нет решения<br>1≤a≤36
{(x-7)²≥1⇒(x-7)²-1≥0⇒(x-7-1)(x-7+1)≥0⇒(x-8)(x-6)≥0⇒x≤6 U x≥8
{(x-7)²≤36⇒(x-7)²-36≤0⇒(x-7-6)(x-7+6)≤0⇒(x-13)(x-1)≤0⇒1≤x≤13
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---------[1]-----------[6]------------(7)----------[8]--------------[13]---------
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x∈[1;6] U [8;13]