Toán Lớp 8: 2x.(3x-5)+15x=25 25x^2-24x=1 ai làm đc em cho 5* vs trl hn ạ

Question

Toán Lớp 8:  2x.(3x-5)+15x=25 25x^2-24x=1 ai làm đc em cho 5* vs trl hn ạ

dantam45 · Answer

~ gửi bạn ~   Giải đáp:   1)  $ left[ begin{matrix} x =  dfrac{5}{3}   x= dfrac{-5}{2} end{matrix} right.$   2)  $ left[ begin{matrix} x =  dfrac{-1}{25}   x=1 end{matrix} right.$   Lời giải và giải thích chi tiết:   2x.(3x&minus;5)+15x=25    &hArr; 6x&sup2;&minus;10x+15x&minus;25=0   &hArr; 6x^&sup2;+5x&minus;25=0   &hArr;6x^&sup2; + 15x &minus; 10x &minus; 25=0   &hArr; 3x(2x+5)&minus;5(2x+5)=0   &hArr; (3x - 5)*(2x + 5) = 0        &hArr;$ left[ begin{matrix} x =  dfrac{5}{3}   x= dfrac{-5}{2} end{matrix} right.$             ____________________________________________        25x^&sup2;&minus;24x=1   &hArr; 25x^&sup2;&minus;24x&minus;1=0   &hArr; 25x^&sup2;&minus;25x+x&minus;1=0   &hArr; 25x(x&minus;1)+(x&minus;1)=0   &hArr; (25x + 1)*(x - 1) = 0            &hArr; $ left[ begin{matrix} x =  dfrac{-1}{25}   x=1 end{matrix} right.$

annhocbichchaubich · Answer

Giải đáp+Lời giải và giải thích chi tiết:    2x.(3x-5)+15x=25     &hArr; 6x&sup2;-10x+15x-25=0     &hArr;6x&sup2;+5x-25=0     &hArr;6x&sup2;+15x-10x-25=0     &hArr;3x(2x+5)-5(2x+5)=0     &hArr;(2x+5)(3x-5)=0     &hArr; ( left[  begin{array}{l}2x+5=0  3x-5= end{array}  right. )      &hArr; ( left[  begin{array}{l}x= dfrac{-5}{2}  x= dfrac{5}{3} end{array}  right. )      Vậy x&isin;{-5/2 , 5/3 }     25x&sup2;-24x=1     &hArr;25x&sup2;-24x-1=0     &hArr;25x&sup2;-25x+x-1=0     &hArr;25x(x-1)+(x-1)=0     &hArr;(x-1)(25x+1)=0     &hArr;  ( left[  begin{array}{l}x-1=0  25x+1=0 end{array}  right. )      &hArr; ( left[  begin{array}{l}x=1  x= dfrac{-1}{25} end{array}  right. )      Vậyx&isin;{1 , -1/25 }