Question

Решите уравнение введения новой переменной
1)(x²-9)²-8(x²-9)+7=0
2)(2x-1)⁴-25(2x-1)²+144=0

Answer 1

$( x ^ { 2 } -9) ^ { 2 } -8( x ^ { 2 } -9) +7 = 0\\ (x ^ { 2 } -9)=t\\t^{2} -8t+7=0\\D=64-4*7=54-28=36\\\sqrt{D} =6t_{1} =\dfrac{8+6}{2} =7t_{2} =\dfrac{8-6}{2} =1\\(x ^ { 2 } -9)=7\\x ^ { 2 }=16\\x=+4,-4\\(x ^ { 2 } -9)=1\\x ^ { 2 }=10\\x=\sqrt{10} ,-\sqrt{10}$

x=4;-4;√10;-√10

${ \left(2x-1 \right) }^{ 4 } -25 { \left(2x-1 \right) }^{ 2 } +144 = 0 \\(2x-1 ) }^{ 2 } =t\\t^2-25t+144=0sqrt{D} =-25^2-4*144=7\\t_{1} =\dfrac{25+7}{2} =16\\t_{2} =\dfrac{25-7}{2} =9\\(2x-1 ) }^{ 2 }=16\\4x ^2-4x+1=16\\4x ^2-4x-15=0\\\sqrt{D}=16-4*4*-15=16\\x_{1} =\dfrac{4+16}{8}=2.5\\x_{2} =\dfrac{4-16}{8}=-1.5\\4x ^2-4x+1=9\\4x ^2-4x-8=0\\\sqrt{D}=16-4*4*-8=12\\x_{1} =\dfrac{4+12}{8}=2\\x_{2} =\dfrac{4-12}{8}=-1$

x=2.5;-1,5;2;-1

Объяснение: