3x²+mx+12=0
D=m²-144>0
(m-12)(m+12)>0
m=12 m=-12
m∈(-∞;-12) U (12;∞)
task/29419479 ----------------------
2^{x+2}*5^{x+2} = 2^{3x}*5^{3x} :
(2*5) ^{x+2} =(2*5)^ 3x ;
10 ^(x+2) = 10^(3x);
x+2 =3x ;
2 =3x -x ;
2 =2x ;
x =2/2 = 1 .
Ответ : 1 .
А) (5a(3a-2b)/(b(3a-2b)=5a/b далее подставьте значения a,b
b) (3c-2d)(3c+2d)/(6cd(3c-2d)=(3c+2d)/6cd также подставьте значения
в) (6x(x+2y)/(5y(x+2y)=6x/5y
г) (x+3y)^2/(4x(x+3y)=(x+3y)/4x
<span>{<span><span>4x−x+2y=1</span><span>3−2x=0,2</span></span></span>
Решение.
Начальные преобразования .
<span><span>{<span><span>4x−x+2y=1</span><span>3−2x=0,2</span></span></span>
</span> <span>{<span><span>3x+2y=1</span><span>−2x+3=0,2</span></span></span><span>
{<span><span>3x+2y=1</span><span>−2x+2,8=0
</span></span></span> Решение методом подстановки.
<span><span>{<span><span>3x+2y=1</span><span>−2x+2,8=0</span></span></span>
</span> <span><span>{<span><span>3x+2y=1</span><span>x=1,4</span></span></span>
</span> <span><span>{<span><span>3<span>(<span>1,4</span>)</span>+2y=1</span><span>x=1,4</span></span></span>
</span> <span><span>{<span><span>2y+3,2=0</span><span>x=1,4</span></span></span>
</span> <span><span>{<span><span>y=−1,6</span><span>x=1,4</span></span></span>
</span> <span>{<span><span>y=−1,6</span><span>x=1,4
</span></span></span> Ответ:
<span><span>(<span><span>75</span>;−<span>85</span></span>)</span>=<span>(<span>1<span>25</span>;−1<span>35</span></span>)</span>≈(1,4;−1,6<span>)</span></span>
0.51х+8=51
0.51х=51-8
0.51х=43
х=43÷0.51 4300÷51=84,4 но это надо проверить .....