ai giúp mình vs
a) x - 1/4=5/8.2/3
b) x/126= -5/9.4/7
ai giúp mình, mình tíc 3 tíc nè
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Ta có: 5:x=-7:y =5phan x=-7 phân ý.Mà x+y=20
Áp dụng tính chất dãy tỉ số bằng nhau ta có:
5phan x = -7 phần y = 5+(-7) trên x+y = -2 trên 20 = -1 phần 10
suy ra 5phan x x -1phan 10 = -1phan 50
7phan y x -1phan 10 = -1 phần 70
17 k nha
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`x^3-8x^2+x+42`
`=x^3-7x^2-x^2+7x-6x+42`
`=(x^3-x^2-6x)-(7x^2-7x-42)`
`=x(x^2-x-6)-7(x^2-x-6)`
`=(x^2-x-6)(x-7)`
`=(x^2-3x+2x-6)(x-7)`
`=[x(x-3)+2(x-3)](x-7)`
`=(x-3)(x+2)(x-7)`
a;x=2/3
b=x=-40 nhớ k nha
ta có:\(x-\frac{1}{4}=\frac{5}{8}\cdot\frac{2}{3}\)
=>\(x-\frac{1}{4}=\frac{5}{12}\)
=>\(\frac{2}{3}\)
b)\(\frac{x}{126}=\frac{-20}{63}\)
=>\(\frac{x}{126}=\frac{-40}{126}\)
=>x=-40