x²+x-12=0
a=1,b=1,c=-12
△=b²-4ac
=1²-4×1×(-12)
=1+48
=49
√△=√49=7
x=(-b±√△)/(2a)
=(-1±7)/2
x1=(-1+7)/2
=3
x2=(-1-7)/2
=-4
x²-√2x-1/4=0
a=1,b=-√2,c=-1/4
△=b²-4ac
=(-√2)²-1×1×(-1/4)
=2+1
=3
√△=√3
x=(-b±√△)/(2a)
=(√2±√3)/2
x1=(√2+√3)/2
x2=(√2-√3)/2
x²+4x+8=2x+11
x²+4x-2x+8-11=0
x²+2x-3=0
a=1,b=2,c=-3
△=b²-4ac
=2²-4×1×(-3)
=4+12
=16
√△=√16=4
x=(-b±√△)/(2a)
=(-2±4)/2
x1=(-2+4)/2
=1
x2=(-2-4)/2
=-3
x(x-4)=2-8x
x²-4x=2-8x
x²-4x+8x-2=0
x²+4x-2=0
a=1,b=4,c=-2
△=b²-4ac
=4²-4×1×(-2)
=16+8
=24
√△=√24=2√6
x=(-b±√△)/(2a)
=(-4±2√6)/2
x1=(-4+2√6)/2
=-2+√6
x2=(-4-2√6)/2
=-2-√6
x²+2x=0
a=1,b=2,c=0
△=b²-4ac
=2²-4×1×0
=4
√△=√4=2
x=(-b±√△)/(2a)
=(-2±2)/2
x1=(-2+2)/2
=0
x2=(-2-2)/2
=-2
x²+2√5x+10=0
a=1,b=2√5,c=10
△=b²-4ac
=(2√5)²-4×1×10
=20-40
=-20
△﹤0,方程无实数解