X2-X-90=0 到X-10)(X+9)=0 之间的过程是什么方法了 没见过啊

X2-X-90=0 到X-10)(X+9)=0 之间的过程是什么方法了 没见过啊 {x2+x x>0 f(x)={ {-x2+x x判断函数的奇偶性{x2+x x>0f(x)= {{-x2+x x 2的x次方+x=0求x2^x+x=10求x 求几道一元二次方程的过程(11)x^2+15x-54=0 x1=-18 x2=3 (12)x^2+11x+18=0 x1=-2 x2=-9 (13)x^2-9x+20=0 x1=4 x2=5 (14)x^2+19x+90=0 x1=-10 x2=-9 (15)x^2-25x+156=0 x1=13 x2=12 (16)x^2-22x+57=0 x1=3 x2=19 (17)x^2-5x-176=0 x1=16 x2=-11 (18)x^2-26x+ 函数f(x)=(x2-2x+9)/x(x (X2-5X)+10X2-50X+24=0X=? (x+3)*(x2+9)*(x-3)=? x2-23x+3=0 x MATLAb编程解方程clear;clcsyms xfor n=1:6X2=solve('(x-1)*(x-2)*(x-3)*(x-4)*(x-5)*(x-6)*(x-7)*(x-8)*(x-9)*(x-10)*(x-11)*(x-12)*(x-13)*(x-14)*(x-15)*(x-16)*(x-17)*(x-18)*(x-19)*(x-20)+1e-n*x^19=0',x);double(X2)end与直接代入n=1,2,...6算出来 2x2-3x-2/3=0 16x2-24x+9=0 x2-4倍根号2x+9=0 3x2+10=2x2+8x 用配方 解方程1/x2+2x+10+1/x2+11x+10+1/x2-13x+10=0 解方程4x2-4x+1=x2+6x+9 7x2-√6x-5=0 2( x2 +1/x2) - 9( x + 1/x) + 14 = 4x2-4x+1=x2+6x+9 x2+x-6/(x2+x)+1=0怎么做 7/x2+x+1/x2-x=0 (x2-x)2+6(x2-x)+9 5(x2-x)=3(x2+x)