tìm x 7x(x^2-x+1)-x^2(7x-7)+3x(2x-1)-2x(3x+15)=-42 27/08/2021 Bởi Gabriella tìm x 7x(x^2-x+1)-x^2(7x-7)+3x(2x-1)-2x(3x+15)=-42
Đáp án: x = 21/13 Giải thích các bước giải: 7x(x^2 – x +1) – x^2 (7x – 7) + 3x( 2x – 1) – 2x(3x + 15 ) = – 42 <=> 7x^3 – 7x^2 + 7x – 7x^3 + 7x^2 + 6x^2 – 3x – 6x^2 – 30x = – 42 <=>(7x^3 – 7x^3) -(7x^2 – 7x^2 – 6x^2 + 6x^2 )+(7x – 3x – 30x) = – 42 <=> – 26x = -42 <=> x = 21/13 Vậy x = 21/13 Bình luận
`7x(x^2-x+1)-x^2(7x-7)+3x(2x-1)-2x(3x+15)=-42` `<=>7x^3-7x^2+7x-7x^3+7x^2+6x^2-3x-6x^2-30x=-42` `<=>-26x=-42` `<=>x=21/13` Vậy `x=21/13` Bình luận
Đáp án:
x = 21/13
Giải thích các bước giải:
7x(x^2 – x +1) – x^2 (7x – 7) +
3x( 2x – 1) – 2x(3x + 15 ) = – 42
<=> 7x^3 – 7x^2 + 7x – 7x^3 + 7x^2 + 6x^2 – 3x – 6x^2 – 30x = – 42
<=>(7x^3 – 7x^3) -(7x^2 – 7x^2 – 6x^2 + 6x^2 )+(7x – 3x – 30x) = – 42
<=> – 26x = -42
<=> x = 21/13
Vậy x = 21/13
`7x(x^2-x+1)-x^2(7x-7)+3x(2x-1)-2x(3x+15)=-42`
`<=>7x^3-7x^2+7x-7x^3+7x^2+6x^2-3x-6x^2-30x=-42`
`<=>-26x=-42`
`<=>x=21/13`
Vậy `x=21/13`