<span>2х</span>²<span>+4х-7=0
Д= 4</span>² -4*2*(-7) =16+56=72
<span>х1= (-4 +</span>√36*√2) /4 = -4 +6√2 / 4 =-1 +1,5√2
<span>х2= -1-1,5</span>√2
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</span><span>
</span>
7х-9=40
7х=40+9
7х=49
х=+7 или-7
3m(2m-1)-(m+3)(m-2)=6m²-3m-m²+2m-3m+6=5m²-4m+6