Question

ajutati maaa ex 8...​

Answer 1

Răspuns:

a. 5($x^{2}$-8)=0 /:5

$x^{2}$-8=0

$x^{2}$=8

x1,x2= ±$2\sqrt{2}$, x1=$2\sqrt{2}$, x2=- $2\sqrt{2}$

b. $\frac{1}{10}$$x^{2}$+$\frac{3}{100}$=$\frac{4}{100}$ ($\frac{1}{25}$) /×100

10$x^{2}$+3=4

10$x^{2}$=4-3

$x^{2}$=$\frac{1}{10}$

x1, x2= ±$\frac{\sqrt{10}}{10}$

c. $\frac{1}{9}$$x^{2}$+3=$\frac{76}{25}$ /×225

25$x^{2}$+675=684

25$x^{2}$=684-675

25$x^{2}$=9

$x^{2}$=$\frac{9}{25}$

x1,x2=$\sqrt{\frac{9}{25} }$=±$\frac{3}{5}$

d. $\frac{3}{10}$$x^{2}$+ $\frac{9}{100}$=$\frac{23}{50}$ /×100

30$x^{2}$+19=46

30$x^{2}$=46-19

30$x^{2}$=27 /:30 =$\frac{27}{30}$ simplifici prin 3

$x^{2}$=$\frac{9}{10}$

x1,x2= ±$\frac{3\sqrt{10} }{10}$

e. $\frac{1}{4}$$x^{2}$+ $\frac{4}{10}$ ($\frac{2}{5}$)=$\sqrt \frac{25}{100}=\sqrt{\frac{1}{4} }$ adica $\frac{1}{2}$

$\frac{1}{4} x^{2} + \frac{2}{5} =\frac{1}{2}$ /×20

5$x^{2}$+8+10

5$x^{2}$=10-8

5$x^{2}$=2 /:5

$x^{2}$= $\frac{2}{5}$

x1,x2= ±$\frac{\sqrt{10} }{5}$

Answer 2

Răspuns:

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. ⓐ 5(x² - 8) = 0 <=> 5x² - 40 = 0 <=> 5x² = 40 <=> x² = 8

ⓑ 0,1x² + 0,03 = 0,04 <=> 0,1x² = 0,01 <=> x² = 0,1

ⓒ 1/9x² + 3 = 76/25 <=> 1/9x² = 76/25 - 3 <=> 1/9x² = 76/25 - 125/25 <=> 1/9x² =  -49/25 <=> x² = -49/25 : 1/9 <=> x² = -1,96 : 1/9 = -17,64/9 : 1/9 = -17,64/9

ⓓ 0,3x² + 0,19 = 23/50 <=> 0,3x² = 23/50 - 9,5/50 <=> 0,3x² = 13,5/50 <=> x² = 13,5/50 : 0,3/1 = 45/50 = 9/10

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