Toán Lớp 8: 16(x+1) ²-9(2x-5) ²=0 mấy bồ cứuuuu emm

Question

Toán Lớp 8:  16(x+1) ²-9(2x-5) ²=0  mấy bồ cứuuuu emm

thanoanghha · Answer

#Hugg   16(x+1)^2-9(2x-5)^2=0   &hArr;16(x^2+2x+1)-9(4x^2-20x+25)=0   &hArr;16x^2+32x+16-36x^2+180x-225=0 &hArr;-20x^2+212x-209=0   &hArr;-20(x^2-53/5x+209/20)=0 &hArr;x&sup2;-53/5+209/20=0   &hArr;x^2-11/10x-19/2x+209/20=0   &hArr;x(x-11/10)-19/2(x-11/10)=0   &hArr;(x-11/10)(x-19/2)=0   1)  x-11/10=0&hArr;x=11/10   2) x-19/2=0&hArr;x=19/2   Vậy x=11/10 v&agrave; x=19/2

lanthuhoa · Answer

Giải đáp: 16(x+1)^2 - 9(2x-5)^2 = 0 <=> [ 4( x +1)]^2 - [3(2x-5)]^2 = 0 <=> ( 4x +4)^2 - (6x - 15)^2 = 0 <=> ( 4x +4 - 6x +15)( 4x +4 + 6x - 15) = 0 <=> (-2x +19)( 10x -11 ) = 0 <=> $ left[ begin{matrix} -2x +19 = 0 10x -11 = 0 end{matrix} right.$$ $ <=> $ left[ begin{matrix} -2x = -19 10x = 11 end{matrix} right.$$ $ <=> $ left[ begin{matrix} x= dfrac{19}{2} x= dfrac{11}{10} end{matrix} right.$ Vậy S={ 19/2 ; 11/10} Áp dụng: A^2 - B^2 = (A-B)(A+B)