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please help me to solve this! :/

"solving quadrating equations by factoring"

 

1. x2+6x-6x=0

2. 4x2-100=0

3. 2x2-13x=-21

4. 4x2-12x=0

5. 4x2+9=12x



Sagot :

1. x(x+3-3)=0
2. 4(x2-25)=0
3. 2x2-13x+21=0
 Final answer: (x-3)(2x-7)
4. 4x(x-3)
5. 4x2-12+9=0
final answer: (2x-3)(2x-3)
Number 1:
[tex] x^{2} +6x-6=0[/tex] (No factor)
[tex] x^{2} +6x=6[/tex]
[tex] x^{2} +6x+(3)^2=6+(3)^2[/tex]
[tex] \sqrt{(x+3)^2}=+or- \sqrt{15} [/tex]
[tex]x+3=+or- \sqrt{15} [/tex]
[tex]x=+or- \sqrt{15} -3[/tex]

Number 2:
[tex]4 x^{2} -100=0[/tex]
[tex](2x+10)(2x-10)=0[/tex]
[tex]2x+10=0[/tex]
[tex]\frac{2x}{2}= -\frac{10}{2} [/tex]
[tex]x=-5[/tex]
[tex]2x-10=0[/tex]
[tex] \frac{2x}{2} = \frac{10}{2} [/tex]
[tex]x=5[/tex]

Number 3:
[tex]2 x^{2} -13=-21[/tex]
[tex]2 x^{2} -13x+21=0[/tex]
[tex](2x-7)(x-3)=0[/tex]
[tex]2x-7=0[/tex]
[tex] \frac{2x}{2} = \frac{7}{2} [/tex]
[tex]x= \frac{7}{2} [/tex]
[tex]x-3=0[/tex]
[tex]x=3[/tex]

Number 4:
[tex]4 x^{2} -12=0[/tex]
[tex]4x(x-3)=0[/tex]
[tex]4x=0[/tex]
[tex]x=0[/tex]
[tex]x-3=0[/tex]
[tex]x=3[/tex]

Number 5:
[tex]4 x^{2} +9=12x[/tex]
[tex]4 x^{2} -12x+9=0[/tex]
[tex](2x-3)^2=0[/tex]
[tex]2x-3=0[/tex]
[tex] \frac{2x}{2} = \frac{3}{2} [/tex]
[tex]x= \frac{3}{2} [/tex]

(Sorry for the late answers... (: )