3.7-3(x-1)=2x
7-3x+3=2x
7+3=3x+2x
10=5x
x=10:5=2
4.6(2x+0.5)=8x-(3x+4)
12x+3=8x-3x-4
12x-8x+3x=-3-4
7x=-7
x=-7:7
x=-1
X^2+2x-3=0
Находим дискриминант:
D = 22 - 4 • 1 • (-3) = 16
Корни уравнения:
x1=(-2+4)/2=1
x2=(-2-4)/2=-3
1/sin²x-1=1/ctg²x
1/sin²x=1/ctg²x+1=1/3,5²+1=1 4/49=53/49
sin²x=49/53
cos²x=1-sin²x=4/53
cosx=-2/√53
√53*(-2/√53)=-2
911
а+ b
<span> 9,2</span>‹а‹<span>9,3
+
0,2</span>‹b‹<span>0,3
_________
9,4</span>‹а+b<span>‹9,6
</span><span>
а- b=а+(- b)
0,2</span>‹ <span>b‹0,3
(умножить на -1)
-0,2›</span> -<span>b› -0,3
-0,3‹-</span><span>b‹ -0,2
9,2‹а‹9,3
+
-0,3‹-</span><span>b‹-0,2
___________
8,9‹а-</span><span>b‹9,1
а</span> *<span>b
9,2‹а‹9,3
*
0,2‹</span><span>b‹0,3
__________
1,84‹а*</span><span>b‹2,79
а/</span> b=а* 1/ <span>b
1/0,2›1/</span><span>b› 1/0,3
1/0,3‹1/</span><span>b‹ 1/0,2
9,2‹а‹9,3
*
1/0,3‹1/</span><span>b‹ 1/0,2
______________
2,76‹а/</span><span>b‹4,65</span>