А)
3x-5=0
3x = 5
x = 5/3
б)
7x-4=0
7x = 4
x = 4/7
в)
7-x = 0
-x = -7
x = 7
г)
5-x=0
-x = -5
x = 5
д)
18-10x=0
-10x = -18
x = 1,8
е)
15-7x = 0
-7x = -15
x = 15/7
ж)
x-2x+3 = 7
x = 4
з)
2x-4x-1 =2
-2x = 3
x = -1,5
и)
3x-5=x
3x-x = 5
2x = 5
x = 2,5
к)
4x-2=x
4x-x = 2
3x = 2
x = 2/3
л)
x-3 = 2x+1
x-2x = 1+3
-x = 4
x = -4
м)
3x+2 = 5x - 7
3x-5x = -7-2
-2x = -9
x = 4,5
-3x2 + 8x + 3 = 0
D = b2 - 4ac
D = 64 + 36 = 100 = 10^2
x1,2 = -b ± √D/2a
x1 = -8 + 10/-6= - 2/6 = - 1/3
x2 = -8 - 10/-6 = 18/6 = 3
Ответ: x1 = - 1/3 ; x2 = 3
1) [(3(n+1)-1)/(5(n+1)+2)]/(3n-1)/(5n+2)=
=(3n+2)(5n+2)/(3n-1)(5n+7)
15n^2+16n+4-15n^2-16n+7=11>0
2) [(n+2)/2n+3)]/(n+1)/(2n+1)=
(n+2)*(2n+1)/[(2n+3)*(n+1)]
2n^2+5n+2-2n^2-3-5n=-1<0
3)