Exercice 1 :
[tex]28*10^{-3} = 0,028[/tex]
[tex] \sqrt{72} = \sqrt{4*18}= \sqrt{2^2*18}=2 \sqrt{18} [/tex]
[tex]( \frac{3}{4})^2- \frac{1}{4}= \frac{9}{16}- \frac{4}{16}= \frac{5}{16} [/tex]
[tex] \frac{2}{3}+ \frac{5}{6}+1= \frac{4}{6}+ \frac{5}{6}+ \frac{6}{6}= \frac{15}{6} [/tex]
x/2 = 6/5 ⇒ 5x = 12 ⇒ x = 12/5
Exercice 2 :
1) E = (3x-5)² - (3x-5) (7x-4)
= 9x² - 30x + 25 - 21x² +12x + 35x - 20
= -12x² + 17x + 5
2) E = (3x-5)² - (3x-5) (7x-4)
= (3x-5)(3x-5) - (3x-5)(7x-4)
= (3x-5) [(3x-5)-(7x-4)]
= (3x-5) (-4x-1)
3) si x=-2 , E = (3*(-2)-5) (-4*(-2)-1)
= (-6-5) (8-1)
= -11 * 7
= -77
Exercice 3 :
1) [tex]( \sqrt{3}+3)^2=( \sqrt{3})^2+2* \sqrt{3}*3+3^2=3+6 \sqrt{3}+9=12+6 \sqrt{3} [/tex]
2) [tex]( \sqrt{72}+3 \sqrt{6})* \sqrt{2}=( \sqrt{36*2}+3 \sqrt{6})* \sqrt{2}=(6 \sqrt{2}+3 \sqrt{6})* \sqrt{2} [/tex]
[tex]=6 \sqrt{2}* \sqrt{2}+3 \sqrt{6}* \sqrt{2}=12+3 \sqrt{12}=12+3 \sqrt{4*3}=12+6 \sqrt{3} [/tex]
3) [tex]A=A'=12+6 \sqrt{3} [/tex]
