a) 7x^2+50x+7 b)12x^2+7x-2 c)15x^2+7x-2 d)4x^2-36x-56 06/08/2021 Bởi Cora a) 7x^2+50x+7 b)12x^2+7x-2 c)15x^2+7x-2 d)4x^2-36x-56
a) `7x^2+50x + 7` `= (7x^2 + 49x) + (x+7)` `= 7x ( x + 7) + 1.(x+7)` `= (7x+1)(x+7)` b) `12x^2+7x-2` `= (12x^2-9x) + (16x-12)` `= 3x(4x – 3) + 4.(4x – 3)` `=( 3x + 4). (4x – 3)` c) `15x^2 + 7x – 2` `=( 15x^2+10x) – (3x+2)` `= 5x(3x+2) – 1.(3x+2)` `= (5x-1)(3x+2)` d) `4x^2 – 36x – 56` `= (4x^2 – 8x) – (28x+56)` `= 4x(x-2) – 28(x+2)` = ? Bình luận
Đáp án: Giải thích các bước giải: a) 7x^2+50x+7 = 7x^2 + 49x + x + 7 = 7x( x + 7) + ( x + 7) = ( x + 7).(7x +1) b) 12x^2+7x-2 = 12x^2 -9x + 16x – 12 = 3x( 4x – 3) + 4( 4x – 3) = (4x – 3).( 3x + 4) c) 15x^2+7x-2 = 15x^2 + 10x – 3x – 2 = 5x( 3x + 2) – (3x + 2) = (3x +2).(5x – 1) d)4x^2-36x-56 = 4x^2 – 28 -8 = 4x^2 – 28x – 8x – 56 = 4x( x-7) – 8(x+7) -> tự nhiên đến đấy bí, thông cảm :< Bình luận
a) `7x^2+50x + 7`
`= (7x^2 + 49x) + (x+7)`
`= 7x ( x + 7) + 1.(x+7)`
`= (7x+1)(x+7)`
b) `12x^2+7x-2`
`= (12x^2-9x) + (16x-12)`
`= 3x(4x – 3) + 4.(4x – 3)`
`=( 3x + 4). (4x – 3)`
c) `15x^2 + 7x – 2`
`=( 15x^2+10x) – (3x+2)`
`= 5x(3x+2) – 1.(3x+2)`
`= (5x-1)(3x+2)`
d) `4x^2 – 36x – 56`
`= (4x^2 – 8x) – (28x+56)`
`= 4x(x-2) – 28(x+2)`
= ?
Đáp án:
Giải thích các bước giải:
a) 7x^2+50x+7
= 7x^2 + 49x + x + 7
= 7x( x + 7) + ( x + 7)
= ( x + 7).(7x +1)
b) 12x^2+7x-2
= 12x^2 -9x + 16x – 12
= 3x( 4x – 3) + 4( 4x – 3)
= (4x – 3).( 3x + 4)
c) 15x^2+7x-2
= 15x^2 + 10x – 3x – 2
= 5x( 3x + 2) – (3x + 2)
= (3x +2).(5x – 1)
d)4x^2-36x-56
= 4x^2 – 28 -8
= 4x^2 – 28x – 8x – 56
= 4x( x-7) – 8(x+7) -> tự nhiên đến đấy bí, thông cảm :<