Sin A = 4/5 = 0,8.
15 = a/ 2*0,8;
15 = a / 1,6;
a = 15 * 1,6;
a = 24
1
1/5*5^2x+5*2^x-250=0
5^x=a
a²+25a-1250=0
a1+a2=-25 U a1*a2=-1250
a1=-50⇒5^x=-50 нет решения
a2=25⇒5^x=25⇒x=2
2
ОДЗ
3-x≥0⇒x≤3
x∈(-∞;3]
2^x²-32=0
2^x²=32
x²=5
x=-√5
x=√5
3-x=0
x=3
Ответ x={-√5;√5;3}
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1) x/3 - x/10 = 10x/30 - 3x/30 = 7x/30 = 7
x/30 = 1
x = 30
2) 2x/9 + 5x/12 = 8x/36 + 15x/36 = 23x/36 = 23
x/36 = 1
x = 36
3) 4x + 5 = (11x - 5)/2
8x + 10 = 11x - 5
15 = 3x
x = 5
Смотри.....................