1. (30-x)·x-(30-x+10)(x-6)=32 2. (2x-10)(x+8)-2x·x=220 3. 3(25-x)-2(25+x)=5 4. 2(10+x)+3·10=54 5. 2x= \frac{7}{4} (x+10)

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вопрос

(30-x)·x-(30-x+10)(x-6)=32
30x - x^2 - (40-x)(x-6) = 32
30x - x^2 - (40x - 6x - x^2 + 6x) = 32
30x - x^2 - 40x + 6x + x^2 - 6x = 32
30x - 40x = 32
-10x = 32
x = -3.2

(2x-10)(x+8)-2x·x=220
2x^2 + 16x - 10x - 80 - 2x^2 = 220
6x - 80 = 220
6x = 300
x = 50

3(25-x)-2(25+x)=5
75 - 3x - 50 - 2x = 5
75 - 50 = 5 + 2x + 3x
25 = 5x
x = 5

2(10+x)+3·10=54
20 + 2x + 30 = 54
50 + 2x = 54
2x = 4
x = 2

2x = \frac{7}{4}(x+10)
8x = 7(x + 10)
8x = 7x + 70
x = 70