可以知道配完方之後會變成 a(x-1)²+8
而 a < 0
展開變成 a(x²-2x+1) + 8 = ax² - 2ax + a + 8
對照係數可知
-2a = b
a + 8 = 5
因此 a = -3 ⇒ b = 6
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可以知道配完方之後會變成 a(x-1)²+8
而 a < 0
展開變成 a(x²-2x+1) + 8 = ax² - 2ax + a + 8
對照係數可知
-2a = b
a + 8 = 5
因此 a = -3 ⇒ b = 6
Users viewing this question
are also looking at these questions 😉
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