已知多项式x²+2x+5的值是7,求多项式3x²+6x+3的值.(提示:x²+2x=2)
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已知多项式x²+2x+5的值是7,求多项式3x²+6x+3的值.(提示:x²+2x=2)
已知多项式x²+2x+5的值是7,求多项式3x²+6x+3的值.
(提示:x²+2x=2)
已知多项式x²+2x+5的值是7,求多项式3x²+6x+3的值.(提示:x²+2x=2)
解
x²+2x+5=7
∴x²+2x=2
∴3x²+6x+3
=3(x²+2x)+3
=3×2+3
=6+3
=9
9,分析请追问。