Sagot :
[tex]s^2+4s-21=0[/tex]
[tex]s^2+4s=21[/tex]
[tex]s^2+4s+(2)^2=21+(2)^2[/tex]
[tex] \sqrt{(s+2)^2}= \sqrt{25} [/tex]
[tex]s+2=5[/tex]
[tex]s=5-2[/tex]
[tex]s=3[/tex]
[tex]4x^2-32x=28[/tex]
[tex] \frac{4x^2-32x}{4}= \frac{28}{4} [/tex]
[tex]x^2-8x+(4)^2=7+(4)^2[/tex][tex] \sqrt{(x-4)^2} = \sqrt{23} [/tex]
[tex]x-4= \sqrt{23} [/tex]
[tex]x= \sqrt{23}+4 [/tex]
[tex]x=- \sqrt{23}+4 [/tex]
[tex]r^2-10r=-17[/tex]
[tex]r^2-10r+(5)^2=-17+(5)^2[/tex]
[tex] \sqrt{(r-5)^2}= \sqrt{8} [/tex]
[tex]r-5= \sqrt{8} [/tex]
[tex]r= \sqrt{8}+5 [/tex]
[tex]r=- \sqrt{8}+5 [/tex]
[tex]m^2+7m- \frac{51}{9}=0 [/tex]
[tex]m^2+7m= \frac{51}{9} [/tex]
[tex]m^2+7m+( \frac{7}{2})^2= \frac{51}{9}+( \frac{7}{2})^2 [/tex]
[tex] \sqrt{(m+ \frac{7}{2})^2 }= \sqrt{ \frac{215}{12} } [/tex]
[tex]m+ \frac{7}{2} = \sqrt{ \frac{215}{12} } [/tex]
[tex]m= \sqrt{ \frac{215}{12}[/tex][tex]- \frac{7}{2} [/tex]
[tex]m= \sqrt{ \frac{215}{12}} -\frac{42}{12} [/tex]
[tex]m=- \sqrt{ \frac{215}{12} }- \frac{42}{12} [/tex]
Phewww! That was hard but fun! :D Hope that helps ^_^
[tex]s^2+4s=21[/tex]
[tex]s^2+4s+(2)^2=21+(2)^2[/tex]
[tex] \sqrt{(s+2)^2}= \sqrt{25} [/tex]
[tex]s+2=5[/tex]
[tex]s=5-2[/tex]
[tex]s=3[/tex]
[tex]4x^2-32x=28[/tex]
[tex] \frac{4x^2-32x}{4}= \frac{28}{4} [/tex]
[tex]x^2-8x+(4)^2=7+(4)^2[/tex][tex] \sqrt{(x-4)^2} = \sqrt{23} [/tex]
[tex]x-4= \sqrt{23} [/tex]
[tex]x= \sqrt{23}+4 [/tex]
[tex]x=- \sqrt{23}+4 [/tex]
[tex]r^2-10r=-17[/tex]
[tex]r^2-10r+(5)^2=-17+(5)^2[/tex]
[tex] \sqrt{(r-5)^2}= \sqrt{8} [/tex]
[tex]r-5= \sqrt{8} [/tex]
[tex]r= \sqrt{8}+5 [/tex]
[tex]r=- \sqrt{8}+5 [/tex]
[tex]m^2+7m- \frac{51}{9}=0 [/tex]
[tex]m^2+7m= \frac{51}{9} [/tex]
[tex]m^2+7m+( \frac{7}{2})^2= \frac{51}{9}+( \frac{7}{2})^2 [/tex]
[tex] \sqrt{(m+ \frac{7}{2})^2 }= \sqrt{ \frac{215}{12} } [/tex]
[tex]m+ \frac{7}{2} = \sqrt{ \frac{215}{12} } [/tex]
[tex]m= \sqrt{ \frac{215}{12}[/tex][tex]- \frac{7}{2} [/tex]
[tex]m= \sqrt{ \frac{215}{12}} -\frac{42}{12} [/tex]
[tex]m=- \sqrt{ \frac{215}{12} }- \frac{42}{12} [/tex]
Phewww! That was hard but fun! :D Hope that helps ^_^
s² + 4s - 21 = 0
(s+7) (s-3) = 0
s+7=0 ; s-3=0
s = -7 ; s = 3
4x² - 32x = 28
x² - 8x = 7
x² - 8x + 16 = 7 + 16
(x-4)² = 23
√(x-4)² = √23
x - 4 = ±√23
x = ±√23 +4
x = √23 +4 ; x = -√23 +4
r² - 10r = -17
r² - 10r + 25 = -17 + 25
(r-5)² = 8
√(r-5)² = √8
r-5 = ±√8
r = ±2√2 +5
r = 2√2 +5 ; r = -2√2 +5
m² +7m - 51/9 = 0
m² +7m = 17/3
m² +7m + (7/2}² = 17/3 + (7/2}²
√(m+7/2)² = √(215/12)
m + 7/2 = ± √(645)/ 6
m = [tex] \frac{ \sqrt{645} }{6} + \frac{7}{2} [/tex] ; m = -\frac{ \sqrt{645} }{6} + \frac{7}{2}
(s+7) (s-3) = 0
s+7=0 ; s-3=0
s = -7 ; s = 3
4x² - 32x = 28
x² - 8x = 7
x² - 8x + 16 = 7 + 16
(x-4)² = 23
√(x-4)² = √23
x - 4 = ±√23
x = ±√23 +4
x = √23 +4 ; x = -√23 +4
r² - 10r = -17
r² - 10r + 25 = -17 + 25
(r-5)² = 8
√(r-5)² = √8
r-5 = ±√8
r = ±2√2 +5
r = 2√2 +5 ; r = -2√2 +5
m² +7m - 51/9 = 0
m² +7m = 17/3
m² +7m + (7/2}² = 17/3 + (7/2}²
√(m+7/2)² = √(215/12)
m + 7/2 = ± √(645)/ 6
m = [tex] \frac{ \sqrt{645} }{6} + \frac{7}{2} [/tex] ; m = -\frac{ \sqrt{645} }{6} + \frac{7}{2}