Решить уравнение 8*7^(2x^2-x) - 7*8^(2x^2-x)=0.
x = 1 или x = (-0,5)
[tex]\Large \boldsymbol{} \displastyle 8*7^{2x^{2} -x} -7*8^{2x^{2} -x}=0[/tex]
[tex]\Large \boldsymbol{} \displastyle 8*7^{2x^{2} -x} =7*8^{2x^{2} -x}[/tex]
[tex]\Large \boldsymbol{} \displastyle 8*7^{2x^{2} -x} :8^{2x^{2} -x}=7\\\\\Large \boldsymbol{} \displastyle 8*\frac{7^{2x^2-x} }{8^{2x^2-x} } =7[/tex]
[tex]\Large \boldsymbol{} \displastyle 8*\left(\frac{7 }{8}\right)^{2x^2-x} =7\\\\\\\left(\frac{7 }{8}\right)^{2x^2-x}=\left(\frac{7}{8}\right)^{1}[/tex]
[tex]\large \boldsymbol{} \displastyle 2x^2-x=1\\\\2x^2-x-1=0\\\\D=b^2-4ac=(-1)^2-4*(-1)*2=1+8=9\\\\x_{1,2}=\frac{-b\±\sqrt{D} }{2a}=\frac{1\±3}{4} \\\\x_1=\frac{1+3}{4}=1\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:x_2=\frac{1-3}{4}=-0,5[/tex]
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Answers & Comments
8*(7/8)^2х²-х=7
(7/8)^2х²-х=7/8^1
2х²-х=1
2х²-х-1=0
Х1=-1/2
Х2=1
Решить уравнение 8*7^(2x^2-x) - 7*8^(2x^2-x)=0.
Ответ:
x = 1 или x = (-0,5)
Объяснение:
[tex]\Large \boldsymbol{} \displastyle 8*7^{2x^{2} -x} -7*8^{2x^{2} -x}=0[/tex]
[tex]\Large \boldsymbol{} \displastyle 8*7^{2x^{2} -x} =7*8^{2x^{2} -x}[/tex]
[tex]\Large \boldsymbol{} \displastyle 8*7^{2x^{2} -x} :8^{2x^{2} -x}=7\\\\\Large \boldsymbol{} \displastyle 8*\frac{7^{2x^2-x} }{8^{2x^2-x} } =7[/tex]
[tex]\Large \boldsymbol{} \displastyle 8*\left(\frac{7 }{8}\right)^{2x^2-x} =7\\\\\\\left(\frac{7 }{8}\right)^{2x^2-x}=\left(\frac{7}{8}\right)^{1}[/tex]
[tex]\large \boldsymbol{} \displastyle 2x^2-x=1\\\\2x^2-x-1=0\\\\D=b^2-4ac=(-1)^2-4*(-1)*2=1+8=9\\\\x_{1,2}=\frac{-b\±\sqrt{D} }{2a}=\frac{1\±3}{4} \\\\x_1=\frac{1+3}{4}=1\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:x_2=\frac{1-3}{4}=-0,5[/tex]