Question

(x²+5x)²+10(x²-5x)+24=0

(x²+x+1)²=3(x⁴+x²+1)

(x-4)(x-5)(x-6)(x-7)=1680

(x+2)(x+3)(x-5)(x-6)=180

2x(8x-1)²(4x-1)=9

hộ em cái ạ !!!!

Answer 1

\(\left(x^2+5x\right)+10\left(x^2-5x\right)+24=0\)

\(\Leftrightarrow\left(x^2+5x\right)-10\left(x^2+5x\right)+24=0\)

\(\Leftrightarrow\left(x^2+5x\right)\left(1-10\right)+14=0\)

\(\Leftrightarrow\left(-9\right)\left(x^2+5x\right)+14=0\)

\(\Leftrightarrow-9\left(x^2+5x\right)=-14\)

\(\Leftrightarrow x^2+5x=\frac{14}{9}\)

\(\Leftrightarrow x=0,2938.....\)

Answer 2

b)     \(-2\left(x-1\right)^2=0\)    => x = 1

Answer 3

(x-4)(x-5)(x-6)(x-7)=1680

=>[(x-4)(x-7)][(x-5)(x-6)]=1680

=>(x² - 11x+28)(x² - 11x+30)=1680

=>(x² - 11x+28)(x² - 11x+28+2)=1680

dat t=x² - 11x+28 ta dc t(t+2)=1680

=>t²+ 2t=1680=>t² +2t- 1680=0

=>t² +42t-40t -1680=0

=>t(t +42)-40(t +42)=0

=>(t -40)(t +42)=0

=>t +42=0    => t={-42;40}

    t -40=0

vi  t=x² - 11x+28 nen x² - 11x+28=40( phan h = mtinh na) => X= {-1;12}

                               x² - 11x+28=-42 (loai)

Answer 4

2x(8x-1)²(4x-1)=9

 => (8x-1)² x (8x²-2x)=9 => (64x² -16x+1) x (8x² - 2x)=9 

đặt t=(8x² - 2x) => 64x² - 16x =8t
ta đc: (8t+1) x t=9 <=> 8t² + t-9 = 0 => (t-1)(8t+9)=0 

=> tu lam na :)

Vậy phương trình có 2nghiệm x=-1/4và x=1/2

 

Answer 5

phuong trinh dau tien khong xac dinh dc dau tao tra tren mang k co

Answer 6

(x+2)(x+3)(x-5)(x-6)=1802) 
=> (x+2)(x-5).(x+3)(x-6) = 180 
=> (x²-3x-10)(x²-3x-18) = 180 
đặt t = x² - 3x ; ta có pt: (t -10)(t -18) = 180 
=> t² - 28t + 180 = 180

=> t² - 28t = 0 => t(t-28)=0 =>t = 0 hoặc t = 28 

 vi t = x²-3x=> co * x²-3x=0 =>  x = 0 hoặc x = 3 

* x²-3x = 28 <=> x²-3x-28 = 0 <=> x = -4 hoặc x = 7 

Vậy pt có 4 nghiệm là: x = 0; x = 3 ; x = -4 ; x = 7