抛物线y=3ax²-2bx+1 经过点(1,-2)(-2,3) 求3a²-2b²的值
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抛物线y=3ax²-2bx+1 经过点(1,-2)(-2,3) 求3a²-2b²的值
抛物线y=3ax²-2bx+1 经过点(1,-2)(-2,3) 求3a²-2b²的值
抛物线y=3ax²-2bx+1 经过点(1,-2)(-2,3) 求3a²-2b²的值
y=3ax^2-2bx+1
y(1)=-2
-2= 3a-2b+1
3a-2b = -3 (1)
y(-2)=3
3=12a+4b-1
3a+b=1 (2)
(1)-(2)
3b=4
b=4/3
a=-1/9
3a^2-2b^2
=1/27 - 32/9
=-95/27
1加1等于11
经过点(1,-2)(-2,3)
-2=3a-2b+1
3=12a+4b+1
解得a=-2/9
b=7/6
所以原式=3*4/81-2*49/36=-139/54