x(x + 1) = 0 3x + 6 = 0 4x – 2 = 3x – 5 x(x – 40 ) + 5x = 20 3x – 6(x – 3) + 4(x + 5)=11 17/07/2021 Bởi Caroline x(x + 1) = 0 3x + 6 = 0 4x – 2 = 3x – 5 x(x – 40 ) + 5x = 20 3x – 6(x – 3) + 4(x + 5)=11
Đáp án: 1) x(x+1)=0 ⇒x=0 hoặc x+1=0 x=-1 Vậy x=-1 2)3x+6=0 3x=-6 x=-2 Vậy x=-2 3)4x-2=3x-5 4x-3x=-5+2 x=-3 Vậy x=-3 3)x(x-40)+5x=20 x²-40x+5x=20 x²-35x=20 x(x-35)=20 ⇒ x=20 hoặc x-35=20 x=55 Vậy x=55 4)3x – 6(x – 3) + 4(x + 5)=11 3x – ( 6x + 18) + (4x + 20) = 11 3x – 6x – 18 + 4x + 20 = 11 ( 3x – 6x + 4x) – ( 18 – 20) = 11 x + 2 = 11 x = 11 – 2 x = 9 Vậy x = 9. Bình luận
a, x(x + 1)= 0 => x= 0 hoặc x+ 1= 0 x = 0 – 1 x = -1 Vậy x ∈ { 0; -1 }. b, 3x + 6 = 0 3x = -6 x= -6 : 3 x= -2 Vậy x= -2. c, 4x – 2 = 3x -5 4x – 3x = -5 + 2 x = -3 Vậy x = -3. e, 3x – 6(x- 3) + 4(x+5) = 11 3x – ( 6x + 18) + (4x + 20) = 11 3x – 6x – 18 + 4x + 20 = 11 ( 3x – 6x + 4x) – ( 18 – 20) = 11 x + 2 = 11 x = 11 – 2 x = 9 Vậy x = 9. (Câu d mik ko bt làm, xl bạn) Bình luận
Đáp án:
1) x(x+1)=0
⇒x=0 hoặc x+1=0
x=-1
Vậy x=-1
2)3x+6=0
3x=-6
x=-2
Vậy x=-2
3)4x-2=3x-5
4x-3x=-5+2
x=-3
Vậy x=-3
3)x(x-40)+5x=20
x²-40x+5x=20
x²-35x=20
x(x-35)=20
⇒ x=20 hoặc x-35=20
x=55
Vậy x=55
4)3x – 6(x – 3) + 4(x + 5)=11
3x – ( 6x + 18) + (4x + 20) = 11
3x – 6x – 18 + 4x + 20 = 11
( 3x – 6x + 4x) – ( 18 – 20) = 11
x + 2 = 11
x = 11 – 2
x = 9
Vậy x = 9.
a, x(x + 1)= 0
=> x= 0 hoặc x+ 1= 0
x = 0 – 1
x = -1
Vậy x ∈ { 0; -1 }.
b, 3x + 6 = 0
3x = -6
x= -6 : 3
x= -2
Vậy x= -2.
c, 4x – 2 = 3x -5
4x – 3x = -5 + 2
x = -3
Vậy x = -3.
e, 3x – 6(x- 3) + 4(x+5) = 11
3x – ( 6x + 18) + (4x + 20) = 11
3x – 6x – 18 + 4x + 20 = 11
( 3x – 6x + 4x) – ( 18 – 20) = 11
x + 2 = 11
x = 11 – 2
x = 9
Vậy x = 9.
(Câu d mik ko bt làm, xl bạn)