X²+5=x²+10x+25
-10x=20
x=-2
0.4^-1=6-x
(2/5)^-1=6-x
5/2=6-x
x=6-5/2
x=3.5
15/x-2+6/x+2=22/x всё умножаем на x
1) 29 : 2 7\11 = 29 : 29\11 = 11
2) 11 - 11.6 = - 0.6
3) - 0.6 + 1 4\9 = -3\5 + 13\9 = 38\45
<span><u> 36 </u> + <u> 88 </u> - <u> 4 </u> =
</span>5 - √7 <span>7+√ 5</span> √7 +√5
= <u> </u><u> 36(5 + </u><span><u>√7) </u> + <u> 88</u></span><span><u>(7-√ 5) </u> - <u> 4</u></span><span><u>(√7- √5) </u> =
</span> (5 - √7) (5+ √7) (7+√ 5)(7-√ 5) (√7 +√5)(√7- √5)
= <u> </u><u> 36(5 + </u><span><u>√7) </u> + <u> 88</u></span><span><u>(7-√ 5) </u> - <u> 4</u></span><span><u>(√7- √5) </u> =
</span> 5² - √7² 7² -√ 5² √7² - √5²
= <u> </u><u> 36(5 + </u><span><u>√7) </u> + <u> 88</u></span><span><u>(7-√ 5) </u> - <u> 4</u></span><span><u>(√7- √5) </u> =
</span> 25 - 7 49 - 5 7 - 5
= <u> </u><u> 36(5 + </u><span><u>√7) </u> + <u> 88</u></span><span><u>(7-√ 5) </u> - <u> 4</u></span><span><u>(√7- √5) </u> =
</span> 18 44 2
= <u> </u><u>2(5 + </u><span><u>√7) </u> + <u> 2</u></span><span><u>(7-√ 5) </u> - <u> 2 </u></span><span><u>(√7- √5) </u> =
</span> 1 1 1
= 2(5 + <span>√7) + 2</span><span>(7-√ 5) - 2 </span>(√7- √5) =
= 10 + 2√7 + 14 - 2√ 5 - 2<span>√7 + 2√5 = </span>10 + 14 = 24