Toán Lớp 8: tìm x ; y x(2x – 1)(x + 5) – (2x^2 + 1)(x + 4,5) = 3,5

Question

Toán Lớp 8:  tìm x ; y x(2x – 1)(x + 5) – (2x^2 + 1)(x + 4,5) = 3,5

hienthucthu97 · Answer

Giải đáp:       Lời giải và giải thích chi tiết:         x     (     2    x    &minus;    1     )      (     x    +    5     )     &minus;     (     2      x      2      +    1     )      (     x    +    4    ,    5     )     =    3    ,    5     x(2x&minus;1)(x+5)&minus;(2x2+1)(x+4,5)=3,5            &rArr;     (     2      x      2      &minus;    x     )      (     x    +    5     )     &minus;    2      x      3      &minus;    9      x      2      &minus;    x    &minus;    4    ,    5    =    3    ,    5     &rArr;(2x2&minus;x)(x+5)&minus;2x3&minus;9x2&minus;x&minus;4,5=3,5            &rArr;    2      x      3      +    10      x      2      &minus;      x      2      &minus;    5    x    &minus;    2      x      3      &minus;    9      x      2      &minus;    x    &minus;    4    ,    5    =    3    ,    5     &rArr;2x3+10x2&minus;x2&minus;5x&minus;2x3&minus;9x2&minus;x&minus;4,5=3,5            &rArr;    &minus;    5    x    &minus;    4    ,    5    =    3    ,    5     &rArr;&minus;5x&minus;4,5=3,5            &rArr;    &minus;    5    x    =    8     &rArr;&minus;5x=8            &rArr;    x    =    &minus;         8/      5