ai giúp e vs ah . Gíup e rùi e cho 5 sao
bài 1
a, (x-2) (x+3) + 2x =(x-2) ² – 2
b, 5(x ² – 2x – 1) + 2(3x-2) =5(x+1) ²
c, (x-1) ² + (x+3) ²= 2(x-2) (x+1) +38
d, (x+2) ² + 3x(x-1) + 7= (2x-1) ² + 5(x+3)
bài2 : giải phương trình
a, x(x+3) ² – 3x = (x+2) ³ + 1
b, (x-3) ³ -2(x-1) = x(x-2) ² – 5x ²
mn giúp e nhanh vs ah , e đg gấp
ai giúp e vs ah . Gíup e rùi e cho 5 sao bài 1 a, (x-2) (x+3) + 2x =(x-2) ² – 2 b, 5(x ² – 2x – 1) + 2(3x-2) =5(x+1) ² c, (x-1) ² + (x+3) ²= 2(x-2)
By Eliza
Đáp án:
Giải thích các bước giải:
BÀI 1
a) (x-2) (x+3) + 2x =(x-2) ² – 2
⇔ x²+3x-2x-6+2x = x²-4x+4-2
⇔ x²+3x-6 = x²-4x+4-2
⇔ x²-x²+3x+4x = 6+4-2
⇔ 7x = 8
⇔ x = 8/7
b) 5(x ² – 2x – 1) + 2(3x-2) =5(x+1) ²
⇔ 5x²-10x-5+6x-4 =5(x²+2x+1)
⇔ 5x²-10x-5+6x-4 =5x²+10x+5
⇔ 5x²-5x²-10x-10x+6x =5+4+5
⇔ -14x =14
⇔ x =14/-14
⇔ x =-1
Vậy S={-1}
c) (x-1) ² + (x+3) ² = 2(x-2) (x+1) +38
⇔x²-2x+1+x²+6x+9 =(2x-4)(x+1)+38
⇔x²-2x+1+x²+6x+9 =2x²+2x-4x-4+38
⇔ 2x²+4x+10 =2x²-2x-4+38
⇔ 2x²-2x²+4x+2x =-4+38-10
⇔ 6x =24
⇔ x =24/6
⇔ x =4
Vậy S={4}
d) (x+2) ² + 3x(x-1) + 7= (2x-1) ² + 5(x+3)
⇔x²+4x+4+3x²-3x+7=4x²-4x+1+5x+15
⇔x+4x²+11=4x²+x+16
⇔x-x+4x²-4x²=16-11
⇔0=5(vô lý)
kết luận x ∈ ∅
BÀI 2
a) x(x+3) ² – 3x = (x+2) ³ + 1
⇔ x(x²+6x+9)-3x =x³+6x²+12x+8+1
⇔ x³+6x²+9x-3x =x³+6x²+12x+8+1
⇔ x³-x³+6x²-6x²+9x-12x-3x=1+8
⇔ 9x-12x-3x =1+8
⇔ -6x =9
⇔ x =9/-6
⇔ x =-3/2
b) (x-3) ³ -2(x-1) = x(x-2) ² – 5x ²
⇔ x³-9x²+27x-27-2x+2 =x(x²-4x+4)-5x²
⇔ x³-9x²+25x-27+2 =x³-4x²+4x-5x²
⇔ x³-9x²+25x-27+2 =x³-9x²+4x
⇔ x³-9x²+25x-x³+9x²-4x =27-2
⇔ 21x =27-2
⇔ 21x =25
⇔ x =25/21
`1a)(x-2)(x+3)+2x=(x-2)^2-2`
`⇔x^2+3x-2x-6+2x=x^2-4x+4-2`
`⇔(x^2-x^2)+(3x-2x+2x+4x)+(-6-4+2)=0`
`⇔7x=8`
`⇔x=8/7`
Vậy `S={8/7}`
`b)5(x^2-2x-1)+2(3x-2)=5(x+1)^2`
`⇔5x^2-10x-5+6x-4=5x^2+10x+5`
`⇔(5x^2-5x^2)+(-10x+6x-10x)+(-5-4-5)=0`
`⇔-14x=14`
`⇔x=-1`
Vậy `S={-1}`
`c)(x-1)^2+(x+3)^2=2(x-2)(x+1)+38`
`⇔x^2-2x+1+x^2+6x+9=2x^2-2x-4+38`
`⇔(x^2+x^2-2x^2)+(-2x+6x+2x)+(1+9+4-38)=0`
`⇔6x=24`
`⇔x=4`
Vậy `S={4}`
`d)(x+2)^2+3x(x-1)+7=(2x-1)^2+5(x+3)`
`⇔x^2+4x+4+3x^2-3x+7=4x^2-4x+1+5x+15`
`⇔(x^2+3x^2-4x^2)+(4x-3x+4x-5x)+(4+7-1-15)=0`
`⇔0x=5`
Vậy pt vô nghiệm
`2a)x(x+3)^2-3x=(x+2)^3+1`
`⇔x(x^2+6x+9)-3x=x^3+6x^2+12x+8+1`
`⇔x^3+6x^2+9x-3x=x^3+6x^2+12x+8+1`
`⇔(x^3-x^3)+(6x^2-6x^2)+(9x-3x-12x)=8+1`
`⇔-6x=9`
`⇔x=-3/2`
Vậy `S={-3/2}`
`b)(x-3)^3-2(x-1)=x(x-2)^2-5x^2`
`⇔x^3-9x^2+27x-27-2x+2=x^3-4x^2+4x-5x^2`
`⇔(x^3-x^3)+(-9x^2+4x^2+5x^2)+(27x-2x-4x)+(-27+2)=0`
`⇔21x=25`
`⇔x=25/21`
Vậy `S={25/21}`