2√2+√50-√98=2√2+√25*2-√49*2=2√2+5√2-7√2=7√2-7√2=0
Множим функцию на 2, соответсвенно интеграл делим на 2.дальше так: 2cos^2 (x)=1+2cos^2 x -1=cos2x-1
![\frac{a^2b^2}{a^2+2ab+b^2}: \frac{ab}{a+b}= \frac{(ab)^2}{(a+b)^2}* \frac{a+b}{ab}= \frac{ab}{a+b}](https://tex.z-dn.net/?f=+%5Cfrac%7Ba%5E2b%5E2%7D%7Ba%5E2%2B2ab%2Bb%5E2%7D%3A+%5Cfrac%7Bab%7D%7Ba%2Bb%7D%3D+%5Cfrac%7B%28ab%29%5E2%7D%7B%28a%2Bb%29%5E2%7D%2A+%5Cfrac%7Ba%2Bb%7D%7Bab%7D%3D+%5Cfrac%7Bab%7D%7Ba%2Bb%7D+)
<span>если а=4-√3, b=4+√3
</span>
![\frac{(4- \sqrt{3}) *(4+ \sqrt{3}) }{(4- \sqrt{3} )+(4+ \sqrt{3} )} = \frac{16-3}{8} = \frac{13}{8}=1,625](https://tex.z-dn.net/?f=%5Cfrac%7B%284-+%5Csqrt%7B3%7D%29+%2A%284%2B+%5Csqrt%7B3%7D%29+%7D%7B%284-+%5Csqrt%7B3%7D+%29%2B%284%2B+%5Csqrt%7B3%7D+%29%7D+%3D+%5Cfrac%7B16-3%7D%7B8%7D+%3D+%5Cfrac%7B13%7D%7B8%7D%3D1%2C625+)
А) 70х=105*4
70х=420
х=420:70
х=6
б) 2х=1/6*3 3/7
2х=1/6*24/7
2х=4/7
х=4/7:2
х=4/7*1/2
х=2/7
в) 7,8х=6,5*3,6
7,8х=23,4
х=23,4:7,8
х=3