<=>[(x+2)(x+5)][(x+3)(x+4)]-24=\(\left(x^2+7x+10\right)\left(\left(x^2+7x+12\right)\right)-24\)(1)
đặt x^2+7x+11=t
=> (1)<=> (t-1)(t+1)-24=t^2-1-24=t^2-25=(t-5)(t+5)
<=> \(\left(x^2+7x+11-5\right)\left(x^2+7x+11+5\right)=\left(x^2+7x+6\right)\left(x^2+7x+16\right)=\left(x+1\right)\left(x+6\right)\left(x^2+7x+16\right)\)
(x+2)(x+3)(x+4)(x+5)=24
(x+x+x+x)(2+3+4+5)=24
(x.4)14=24
x.4=24:14
x.4=2
x=2:4
X=1/2
(x+2)(x+5)(x+3)(x+4)-24=(X^2+7x+10)(x^2+7x+12)-24
Đặt x^2+7x+10=t đa thức đã cho trở thành t*(t+2)-24=t^2+2t-24=t^2+6t-4t-24=t*(t+6)-4(t+6)
=(t+6)(t-4)
Thay ngược trở lại ta được (x2 +7x+10+6)(x2 +7x+10-4)=(x^2+7x+6)
dunghandsome là thằng ngu nhất thế giới
\(A=\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)-24\)
\(=\left[\left(x+2\right)\left(x+5\right)\right].\left[\left(x+3\right)\left(x+4\right)\right]-24\)
\(=\left(x^2+7x+10\right)\left(x^2+7x+12\right)-24\)
Đặt: \(x^2+7x+11=t\)
Khi đó ta có: \(A=\left(t-1\right)\left(t+1\right)-24=t^2-25=\left(t-5\right)\left(t+5\right)\)
Thay trở lại ta có: \(A=\left(x^2+7x+6\right)\left(x^2+7x+16\right)\)
\(A=\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)-24\)
\(=\left[\left(x+2\right)\left(x+5\right)\right]\left[\left(x+3\right)\left(x+4\right)\right]-24\)
\(=\left(x^2+7x+10\right)\left(x^2+7x+12\right)-24\)
Đặt: \(x^2+7x+11=t\)
Khi đó ta có: \(A=\left(t-1\right)\left(t+1\right)-24=t^2-25=\left(t-5\right)\left(t+5\right)\)
Thay trở lại ta có: \(A=\left(x^2+7x+6\right)\left(x^2+7x+16\right)\)