Question

Zadanie w załączniku pomocy daje naj

Answer 1

Zad.3 
a)3x+y=5
   x-2y=-3

y=5-3x
x=-3+2y

y=5-3(-3+2y)
x=-3+2y

y=5+9-6y
x=-3+2y

y+6y=14
x=-3+2y

7y=14       /:7
x=-3+2y

y=2
x=-3+2*2

x=1
y=2

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b)0,5x+0,75y=2
   0,25y=3+x

1/2x+3/4y=2       /*2
1/4y=3+4            /*4

x=4-1,5y
y=12+4x

x=4-1,5y
y=12+4(4-1,5y)

x=4-1,5y
y=12+16-6y

x=4-1,5y
y+6y=28

x=4-1,5y
7y=28       /:7

x=4-1,5y
y=4

x=4-1,5*4
y=4

x=-2
y=4
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c)
zad.
a)
(2x-3)(3+2x)≤(2x-1)(2x-1)
6x+4x²-9-6x≤4x²-4x+1
4x²-4x²+4x≤1+9
4x≤10     /:4
x≤10/4
x≤2 1/2
c)
(3x+5)²<9(x-2)²
(3x+5)(3x+5)<9(x-2)(x-2)
9x²+15x+15x+25<9(x²-4x+4)
9x²+30x+25<9x²-36x+36
9x²-9x²+30²x+36x<36-25
66x<11              /:66
x<11/66
x<1/6
d)
3<-4(3-x)²-(2x+3)(3-2x)
3<-4(3-x)(3-x)-(6x-4x²+9-6x)
3<-4(9-6x+x²)+4x²-9
3<-36+24x-4x²+4x²-9
3+45<24x
48<24x    /:24
x>2