如题所述
y=2x^2+1
å½y=1æ¶ï¼x=0
å½y=7æ¶ï¼2x^2+1=7
x^2=3
x=屉3
å®ä¹åä¸åå¼åç¸åçå½æ°æï¼
y=2x^2+1; D={0,â3}
y=2x^2+1: D={0,-â3}
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