1)3х *2х>(1/36)2х-1 2)2х-1+2х-2+2х-3=896 3)32х+1+9=3х+3+3х 4)18,23х-2=0,272 5)3*4х -5*6х+2*9х=0 6)log1/3 (2-5x)> -2 7)log2 (2x+2)+ log(x-5)=7log75 8)log31/x +log3√x= -1 9)log16x +log4x+log2x=7 10)xlog3x-4=1/27 11)log√3(x-y)=2 2x-2 *5y-1=40 12)2log2(3x-4)=8 log9(x2-y2)-log9(x+y)=0,5

Лебедев Дмитрий Сергеевич

Учитель математики

Проверено учителем

Ниже приведены подробные решения представленных уравнений и неравенств. 1) 3x2x>(136)2x13 to the x-th power center dot 2 to the x-th power is greater than open paren 1 over 36 end-fraction close paren raised to the 2 x minus 1 power Используем свойства степеней: axbx=(ab)xa to the x-th power center dot b to the x-th power equals open paren a b close paren to the x-th power и 136=6-21 over 36 end-fraction equals 6 to the negative 2 power . (32)x>(6-2)2x1open paren 3 center dot 2 close paren to the x-th power is greater than open paren 6 to the negative 2 power close paren raised to the 2 x minus 1 power 6x>6-4x+26 to the x-th power is greater than 6 raised to the negative 4 x plus 2 powerТак как основание 6>16 is greater than 1, знак неравенства сохраняется: x>-4x+2x is greater than negative 4 x plus 2 5x>2x>0,45 x is greater than 2 ⟹ bold x is greater than 0 comma 42) 2x1+2x2+2x3=8962 raised to the x minus 1 power plus 2 raised to the x minus 2 power plus 2 raised to the x minus 3 power equals 896 Вынесем за скобки степень с наименьшим показателем 2x32 raised to the x minus 3 power: 2x3(22+21+1)=8962 raised to the x minus 3 power open paren 2 squared plus 2 to the first power plus 1 close paren equals 896 2x3(4+2+1)=8962 raised to the x minus 3 power open paren 4 plus 2 plus 1 close paren equals 896 2x37=8962 raised to the x minus 3 power center dot 7 equals 896 2x3=1282x3=272 raised to the x minus 3 power equals 128 ⟹ 2 raised to the x minus 3 power equals 2 to the seventh power x3=7x=10x minus 3 equals 7 ⟹ bold x equals 103) 32x+1+9=3x+3+3x3 raised to the 2 x plus 1 power plus 9 equals 3 raised to the x plus 3 power plus 3 to the x-th power Приведем к общему основанию 3x3 to the x-th power: 3(3x)2+9=273x+3x3 center dot open paren 3 to the x-th power close paren squared plus 9 equals 27 center dot 3 to the x-th power plus 3 to the x-th power Пусть 3x=t3 to the x-th power equals t ( t>0t is greater than 0): 3t228t+9=03 t squared minus 28 t plus 9 equals 0 Дискриминант D=(-28)2439=784108=676=262cap D equals open paren negative 28 close paren squared minus 4 center dot 3 center dot 9 equals 784 minus 108 equals 676 equals 26 squared. t1=28+266=9;t2=28266=13t sub 1 equals the fraction with numerator 28 plus 26 and denominator 6 end-fraction equals 9 ; space t sub 2 equals the fraction with numerator 28 minus 26 and denominator 6 end-fraction equals one-third Возвращаемся к замене:

  1. 3x=9x1=23 to the x-th power equals 9 ⟹ bold x sub 1 equals 2 3x=13x2=-13 to the x-th power equals one-third ⟹ bold x sub 2 equals negative 1

4) 18,23x2=0,27218 comma 2 raised to the 3 x minus 2 power equals 0 comma 272 (Предположительно, в условии опечатка в числах, так как 18,218 comma 2 и 0,2720 comma 272 не являются степенями одного числа. Прологарифмируем обе части): (3x2)lg(18,2)=lg(0,272)open paren 3 x minus 2 close paren l g open paren 18 comma 2 close paren equals l g open paren 0 comma 272 close paren 3x2=lg(0,272)lg(18,2)3 x minus 2 equals l g open paren 0 comma 272 close paren over l g open paren 18 comma 2 close paren end-fraction x=13(lg(0,272)lg(18,2)+2)bold x equals one-third open paren l g open paren 0 comma 272 close paren over l g open paren 18 comma 2 close paren end-fraction plus 2 close paren 5) 34x56x+29x=03 center dot 4 to the x-th power minus 5 center dot 6 to the x-th power plus 2 center dot 9 to the x-th power equals 0 Это однородное уравнение. Разделим на 9x9 to the x-th power: 3(49)x5(69)x+2=03 center dot open paren four-nineths close paren to the x-th power minus 5 center dot open paren six-nineths close paren to the x-th power plus 2 equals 0 3(23)2x5(23)x+2=03 center dot open paren two-thirds close paren raised to the 2 x power minus 5 center dot open paren two-thirds close paren to the x-th power plus 2 equals 0 Пусть (23)x=topen paren two-thirds close paren to the x-th power equals t : 3t25t+2=0t1=1,t2=233 t squared minus 5 t plus 2 equals 0 ⟹ t sub 1 equals 1 comma t sub 2 equals two-thirds

  1. (23)x=1x1=0open paren two-thirds close paren to the x-th power equals 1 ⟹ bold x sub 1 equals 0 (23)x=23x2=1open paren two-thirds close paren to the x-th power equals two-thirds ⟹ bold x sub 2 equals 1

6) log1/3(25x)>-2log base 1 / 3 of open paren 2 minus 5 x close paren is greater than negative 2 ОДЗ: 25x>0x<0,42 minus 5 x is greater than 0 ⟹ x is less than 0 comma 4. Так как основание 1/3<11 / 3 is less than 1, знак меняется: 25x<(1/3)-22 minus 5 x is less than open paren 1 / 3 close paren to the negative 2 power 25x<9-5x<7x>-1,42 minus 5 x is less than 9 ⟹ negative 5 x is less than 7 ⟹ x is greater than negative 1 comma 4С учетом ОДЗ: x(-1,4;0,4)bold x is an element of open paren negative 1 comma 4 ; 0 comma 4 close paren 7) log2(2x+2)+log2(x5)=7log75log base 2 of open paren 2 x plus 2 close paren plus log base 2 of open paren x minus 5 close paren equals 7 log base 7 of 5 (Вероятно, в правой части опечатка и должно быть основание 2. Если решать "как есть", 7log75=57 log base 7 of 5 equals 5): ОДЗ: x>5x is greater than 5. log2((2x+2)(x5))=5log base 2 of open paren open paren 2 x plus 2 close paren open paren x minus 5 close paren close paren equals 5 (2x+2)(x5)=25=32open paren 2 x plus 2 close paren open paren x minus 5 close paren equals 2 to the fifth power equals 32 2x210x+2x1032=02x28x42=02 x squared minus 10 x plus 2 x minus 10 minus 32 equals 0 ⟹ 2 x squared minus 8 x minus 42 equals 0 x24x21=0(x7)(x+3)=0x squared minus 4 x minus 21 equals 0 ⟹ open paren x minus 7 close paren open paren x plus 3 close paren equals 0С учетом ОДЗ ( x>5x is greater than 5): x=7bold x equals 7 8) log31x+log3x=-1log base 3 of 1 over x end-fraction plus log base 3 of the square root of x end-root equals negative 1 ОДЗ: x>0x is greater than 0. log3x+12log3x=-1negative log base 3 of x plus one-half log base 3 of x equals negative 1 12log3x=-1log3x=2negative one-half log base 3 of x equals negative 1 ⟹ log base 3 of x equals 2 x=32x=9x equals 3 squared ⟹ bold x equals 99) log16x+log4x+log2x=7log base 16 of x plus log base 4 of x plus log base 2 of x equals 7 Приведем к основанию 2: 14log2x+12log2x+log2x=7one-fourth log base 2 of x plus one-half log base 2 of x plus log base 2 of x equals 7 (14+24+44)log2x=7open paren one-fourth plus two-fourths plus four-fourths close paren log base 2 of x equals 7 74log2x=7log2x=4seven-fourths log base 2 of x equals 7 ⟹ log base 2 of x equals 4 x=24x=16x equals 2 to the fourth power ⟹ bold x equals 1610) xlog3x4=127x raised to the log base 3 of x minus 4 power equals 1 over 27 end-fraction Прологарифмируем обе части по основанию 3: log3(xlog3x4)=log33-3log base 3 of open paren x raised to the log base 3 of x minus 4 power close paren equals log base 3 of 3 to the negative 3 power (log3x4)log3x=-3open paren log base 3 of x minus 4 close paren log base 3 of x equals negative 3 Пусть log3x=tlog base 3 of x equals t: t24t+3=0t1=3,t2=1t squared minus 4 t plus 3 equals 0 ⟹ t sub 1 equals 3 comma t sub 2 equals 1

  1. log3x=3x1=27log base 3 of x equals 3 ⟹ bold x sub 1 equals 27 log3x=1x2=3log base 3 of x equals 1 ⟹ bold x sub 2 equals 3

11) Система: log3(xy)=2log base the square root of 3 end-root of open paren x minus y close paren equals 2 и 2x25y1=402 raised to the x minus 2 power center dot 5 raised to the y minus 1 power equals 40

  1. Из первого: xy=(3)2=3x=y+3x minus y equals open paren the square root of 3 end-root close paren squared equals 3 ⟹ x equals y plus 3 . Подставим во второе: 2y+325y1=402 raised to the y plus 3 minus 2 power center dot 5 raised to the y minus 1 power equals 40
    2y+15y1=402y1225y1=402 raised to the y plus 1 power center dot 5 raised to the y minus 1 power equals 40 ⟹ 2 raised to the y minus 1 power center dot 2 squared center dot 5 raised to the y minus 1 power equals 40 4(25)y1=4010y1=1014 center dot open paren 2 center dot 5 close paren raised to the y minus 1 power equals 40 ⟹ 10 raised to the y minus 1 power equals 10 to the first power y1=1y=2;x=5y minus 1 equals 1 ⟹ bold y equals 2 ; space bold x equals 5

12) Система: 2log2(3x4)=82 log base 2 of open paren 3 x minus 4 close paren equals 8 и log9(x2y2)log9(x+y)=0,5log base 9 of open paren x squared minus y squared close paren minus log base 9 of open paren x plus y close paren equals 0 comma 5

  1. Из первого: log2(3x4)=43x4=163x=20x=623log base 2 of open paren 3 x minus 4 close paren equals 4 ⟹ 3 x minus 4 equals 16 ⟹ 3 x equals 20 ⟹ bold x equals 6 and two-thirds . Из второго: log9(xy)(x+y)x+y=0,5log base 9 of the fraction with numerator open paren x minus y close paren open paren x plus y close paren and denominator x plus y end-fraction equals 0 comma 5
    log9(xy)=0,5xy=90,5=3log base 9 of open paren x minus y close paren equals 0 comma 5 ⟹ x minus y equals 9 raised to the 0 comma 5 power equals 3 623y=3y=3236 and two-thirds minus y equals 3 ⟹ bold y equals 3 and two-thirds

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