Tìm x, biết: a,(3x – 1) (2x +7) – (x+1) (6x-5) = 16 b, (10x +9) x – (5x-1) (2x+3) = 8 26/07/2021 Bởi Everleigh Tìm x, biết: a,(3x – 1) (2x +7) – (x+1) (6x-5) = 16 b, (10x +9) x – (5x-1) (2x+3) = 8
$a.(3x – 1)(2x +7) – (x+1)(6x-5) = 16 \\⇔6x^2+19x-7-6x^2-x+5=16 \\⇔18x-2=16 \\⇔18x=18 \\⇔x=1 \\ Vậy\ x=1 \\b.(10x+9)x-(5x-1)(2x+3)=8 \\⇔10x^2+9x-10x^2-13x+3=8 \\⇔-4x+3=8 \\⇔-4x=5 \\⇔x=\dfrac{-5}{4} \\Vậy\ x=\dfrac{-5}{4}$ Bình luận
a,(3x – 1) (2x +7) – (x+1) (6x-5) = 16 `<=> 6x^2-2x+21x-6x^2-6x+5x+5=16` `<=> 18x-2=16` `<=> 18x=18` `<=> x=1` b, (10x +9) x – (5x-1) (2x+3) = 8 `<=> 10x^2+9x-10x^2+2x-15x+3=8` `<=> -4x+3=8` `<=> -4x=5 `<=> x=-5/4` Bình luận
$a.(3x – 1)(2x +7) – (x+1)(6x-5) = 16 \\⇔6x^2+19x-7-6x^2-x+5=16 \\⇔18x-2=16 \\⇔18x=18 \\⇔x=1 \\ Vậy\ x=1 \\b.(10x+9)x-(5x-1)(2x+3)=8 \\⇔10x^2+9x-10x^2-13x+3=8 \\⇔-4x+3=8 \\⇔-4x=5 \\⇔x=\dfrac{-5}{4} \\Vậy\ x=\dfrac{-5}{4}$
a,(3x – 1) (2x +7) – (x+1) (6x-5) = 16
`<=> 6x^2-2x+21x-6x^2-6x+5x+5=16`
`<=> 18x-2=16`
`<=> 18x=18`
`<=> x=1`
b, (10x +9) x – (5x-1) (2x+3) = 8
`<=> 10x^2+9x-10x^2+2x-15x+3=8`
`<=> -4x+3=8`
`<=> -4x=5
`<=> x=-5/4`