Toán TÌM X( đặt ẩn phụ): (X MŨ2 + 5x) ² – 2.( X MŨ2 + 5X) = 24 09/07/2021 By Jade TÌM X( đặt ẩn phụ): (X MŨ2 + 5x) ² – 2.( X MŨ2 + 5X) = 24
`(x^2+5x)^2-2(x^2+5x)-24=0` Đặt `x^2+5x=a` `=>a^2-2a+1-25=0` `=>(a-1)^2-5^2=0` `=>(a-1-5)(a-1+5)=0` `=>(a-6)(a+4)=0` `=>(x^2+5x-6)(x^2+5x+4)=0` `=>(x-1)(x+6)(x+1)(x+4)=0` `=>`\(\left[ \begin{array}{l}x=-6\\x=-1\\x=1\\x=-4\\\end{array} \right.\) HỌC TỐT Trả lời
`(x^2+5x)^2-2(x^2+5x)-24=0` Đặt `x^2+5x=t` `=>t^2-2t+1-25=0` `=>(t-1)^2-5^2=0` `=>(t-1-5)(t-1+5)=0` `=>(t-6)(t+4)=0` `=>(x^2+5x-6)(x^2+5x+4)=0` `=>(x-1)(x+6)(x+1)(x+4)=0` `=>`\(\left[ \begin{array}{l}x=-6\\x=-1\\x=1\\x=-4\\\end{array} \right.\) Trả lời
`(x^2+5x)^2-2(x^2+5x)-24=0`
Đặt `x^2+5x=a`
`=>a^2-2a+1-25=0`
`=>(a-1)^2-5^2=0`
`=>(a-1-5)(a-1+5)=0`
`=>(a-6)(a+4)=0`
`=>(x^2+5x-6)(x^2+5x+4)=0`
`=>(x-1)(x+6)(x+1)(x+4)=0`
`=>`\(\left[ \begin{array}{l}x=-6\\x=-1\\x=1\\x=-4\\\end{array} \right.\)
HỌC TỐT
`(x^2+5x)^2-2(x^2+5x)-24=0`
Đặt `x^2+5x=t`
`=>t^2-2t+1-25=0`
`=>(t-1)^2-5^2=0`
`=>(t-1-5)(t-1+5)=0`
`=>(t-6)(t+4)=0`
`=>(x^2+5x-6)(x^2+5x+4)=0`
`=>(x-1)(x+6)(x+1)(x+4)=0`
`=>`\(\left[ \begin{array}{l}x=-6\\x=-1\\x=1\\x=-4\\\end{array} \right.\)