`a,`
`√(1,69) .(2√x + √(81/121))=13/10`
`√(169/100) .(2√x + 9/11)=13/10`
`13/10 .(2√x + 9/11)=13/10`
`2√x + 9/11=13/10 : 13/10`
`2√x + 9/11=1`
`2√x =1+ 9/11`
`2√x =11/11+ 9/11`
`2√x =20/11`
`√x =20/11 :2`
`√x =20/11 . 1/2`
`√x =10/11`
`⇒x=(10/11)^2`
`⇒x=100/121`
Vậy `x=100/121`
`b,`
`(2x^2-3)(3x^2-1/(0,12))(x^2+1)=0`
`\text{Để}` `(2x^2-3)(3x^2-1/(0,12))(x^2+1)=0`
`\text{Ta có:}`
`+) (2x^2-3)=0`
`+) (3x^2-1/(0,12))=0`
`+) (x^2+1)=0`
`+) 2x^2-3=0`
`⇒2x^2=0+3`
`2x^2=3`
`x^2=3:2`
`x^2=3/2`
`⇒x=±√(3/2)`
`+) 3x^2-1/(0,12)=0`
`⇒ 3x^2-25/3=0`
`⇒3x^2=0+25/3`
`⇒3x^2=25/3`
`x^2=25/3:3`
`x^2=25/3 . 1/3`
`x^2=25/9`
`x^2=(±5/3)^2`
`x=±5/3`
`+) x^2+1=0`
`x^2=0-1`
`x^2=-1` (Vô lý và `x^2 ≥ 0` mà `-1 ≤ 0`)
Vậy `x=±√(3/2)` hoặc `x=±5/3`
`c,`
`x-5√x=0`
`⇒√x(√x-5)=0`
`+) √x=0 ⇒ x=0`
`+) √x-5=0 ⇒ √x=0+5 ⇒ √x=5 ⇒ x=25`
Vậy `x=0` hoặc `x=25`
`d,`
`2x^7=3x^9`
`⇒2x^7-3x^9=0`
`⇔ 2x=3x ∈ {-1; 0; 1}`
`2x^7-3x^9=-1`
`⇔x=1`
`2x^7-3x^9=0`
`⇔x=0`
`2x^7-3x^9=1`
`⇔x=-1`
Vậy `x ∈ {1; 0; -1}`
Cho mình xin câu trả lời hay nhất nha 🥰🥰🥰
Chúc bạn học tốt!!!
`@Nhi`
