a, 4x^2-4x-(1-x)=0
b, 5x^2+10x-4x-8=0
c, x^a2 +7x-4x-28=0
d, 1/2x^2 – 1/8x -3(1/6x-1/4)=0
e, x^2+5x-6=0
g, x^2-3x+2=0
h, 2x^2 -4x +2=0
a, 4x^2-4x-(1-x)=0
b, 5x^2+10x-4x-8=0
c, x^a2 +7x-4x-28=0
d, 1/2x^2 – 1/8x -3(1/6x-1/4)=0
e, x^2+5x-6=0
g, x^2-3x+2=0
h, 2x^2 -4x +2=0
Đáp án:
Giải thích các bước giải:
`a, 4x^2-4x-(1-x)=0`
`<=>4x(x-1)+(x-1)=0`
`<=>(x-1)(4x+1)=0`
`=>x=1` hoặc `x=-1/4`
`b, 5x^2+10x-4x-8=0`
`<=>5x(x+2)-4(x+2)=0`
`<=>(x+2)(5x-4)=0`
`=>x=-2` hoặc `x=4/5`
`c, x^2 +7x-4x-28=0`
`<=>x(x+7)-4(x+7)=0`
`<=>(x+7)(x-4)=0`
`=>x=4` hoặc `x=-7`
`d, 1/2x^2 – 1/8x -3(1/6x-1/4)=0`
`<=>x^2-1/4x-x+3/2=0`
`<=>x^2-5/4x+3/2=0`
`<=>4x^2-5x+6=0`
`<=>4x^2-2.2x.5/4+25/16+71/16=0`
`<=>(2x-5/4)^2+71/16=0` vô lý
=>pt vô nghiệm
`e, x^2+5x-6=0 `
`<=>x^2-x+6x-6=0`
`<=>x(x-1)+6(x-1)=0`
`<=>(x-1)(x+6)=0`
`=>x=1` hoặc `x=-6`
`g, x^2-3x+2=0`
`<=>x^2-x-2x+2=0`
`<=>x(x-1)-2(x-1)=0`
`<=>(x-1)(x-2)=0`
`=>x=1` hoặc `x=2`
`h, 2x^2 -4x +2=0`
`<=>2(x^2-2x+1)=0`
`<=>2(x-1)^2=0`
`=>x-1=0`
`=>x=1`
Đáp án:
Giải thích các bước giải:
a,4x2−4x−(1−x)=0a,4×2-4x-(1-x)=0
⇔4x(x−1)+(x−1)=0⇔4x(x-1)+(x-1)=0
⇔(x−1)(4x+1)=0⇔(x-1)(4x+1)=0
⇒x=1⇒x=1 hoặc x=−14x=-14
b,5x2+10x−4x−8=0b,5×2+10x-4x-8=0
⇔5x(x+2)−4(x+2)=0⇔5x(x+2)-4(x+2)=0
⇔(x+2)(5x−4)=0⇔(x+2)(5x-4)=0
⇒x=−2⇒x=-2 hoặc x=45x=45
c,x2+7x−4x−28=0c,x2+7x-4x-28=0
⇔x(x+7)−4(x+7)=0⇔x(x+7)-4(x+7)=0
⇔(x+7)(x−4)=0⇔(x+7)(x-4)=0
⇒x=4⇒x=4 hoặc x=−7x=-7
d,12x2−18x−3(16x−14)=0d,12×2-18x-3(16x-14)=0
⇔x2−14x−x+32=0⇔x2-14x-x+32=0
⇔x2−54x+32=0⇔x2-54x+32=0
⇔4x2−5x+6=0⇔4×2-5x+6=0
⇔4x2−2.2x.54+2516+7116=0⇔4×2-2.2x.54+2516+7116=0
⇔(2x−54)2+7116=0⇔(2x-54)2+7116=0 vô lý
=>pt vô nghiệm
e,x2+5x−6=0e,x2+5x-6=0
⇔x2−x+6x−6=0⇔x2-x+6x-6=0
⇔x(x−1)+6(x−1)=0⇔x(x-1)+6(x-1)=0
⇔(x−1)(x+6)=0⇔(x-1)(x+6)=0
⇒x=1⇒x=1 hoặc x=−6x=-6
g,x2−3x+2=0g,x2-3x+2=0
⇔x2−x−2x+2=0⇔x2-x-2x+2=0
⇔x(x−1)−2(x−1)=0⇔x(x-1)-2(x-1)=0
⇔(x−1)(x−2)=0⇔(x-1)(x-2)=0
⇒x=1⇒x=1 hoặc x=2x=2
h,2x2−4x+2=0h,2×2-4x+2=0
⇔2(x2−2x+1)=0⇔2(x2-2x+1)=0
⇔2(x−1)2=0⇔2(x-1)2=0
⇒x−1=0⇒x-1=0
⇒x=1