Question

(-2 икс-5)(0,3икс+2,7)=0​

Answer 1

Відповідь:

( - 2x - 5) * (0.3x + 2.7) = 0

( - 2x - 5) * (

3

10

x +

27

10

) = 0

( -

3

5

x2 -

69

10

x -

27

2

) = 0

-

3

5

x2 -

69

10

x -

27

2

= 0

- 6x2 - 69x - 135 = 0

- 2x2 - 23x - 45 = 0

a = ‑ 2 b = ‑ 23 c = ‑ 45

D = b² - 4 * a * c

D = (‑ 23)² - 4 * (‑ 2) * (‑ 45) = 529 - 360 = 169

D > 0 => x1,2 =

-b ± √D

2 * a

x1,2 =

23 ± √169

2 * (‑ 2)

=

23 ± 13

(‑ 4)

x1 =

23 - 13

(‑ 4)

=

10

(‑ 4)

= ‑

5

2

x2 =

23 + 13

(‑ 4)

=

36

(‑ 4)

= ‑ 9

x1 = ‑

5

2

= ‑ 2

1

2

(x1 = -2.5)

x2 = ‑ 9

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