因式分解和展開問題 (5分)

其實第一同第三題可以用計數機幫手計的...f50係內置的,3600pv果d要自己set的

第一題
let y=x-1
y^2-5y-24
=(y-8)(y+3)
=(x-1-8)(x-1+3)
=(x-9)(x+2)

Q2
(7-a)(a^2+7a+49)
=7a^2+49a+343-a^3-7a^2-49a
=-a^3+343

Q3
-16s^2+24s-9
=-(16s^2-24s+9)
=-(4s-3)^2

因式分解(x-1)^2-5(x-1)-24

(x-1)^2-5(x-1)-24
=(x-1)^2-8(x-1)+3(x-1)-24
=(x-1)(x-1-8)+3(x-1-8)
=(x-1)(x-9)+3(x-9)
=(x-9)(x-1+3)
=(x-9)(x+2)

展開(7-a)(a^2+7a+49)

(7-a)(a^2+7a+49)
=7(a^2+7a+49)-a(a^2+7a+49)
=7*a^2+7*7a+7*49-a*a^2-a*7a-a*49
=7a^2+49a+343-a^3-7a^2-49a
=-a^3+7a^2-7a^2+49a-49a+343
=-a^3+343

因式分解-16s^2+24s-9

-16s^2+24s-9
=-(16s^2-24s+9)
=-((4s)^2-2*4s*3+3^2)
=-(4s-3)^2

(x-1)^2-5(x-1)-24=(x-1-8)(x-1+3)=(x-9)(x+2)

(7-a)(a^2+7a+49)
=7a^2+49a+343-a^3-7a^2-49a
=7a^2-7a^2+49a-49a+343-a^3
=343-a^3

-16s^2+24s-9=-(16s^2-24s+9)
=-(4s-3)^2

(x-1)^2 - 5(x-1) - 24
=X^2-2X+1 -5X+5 -24
=X^2 -7X -18

----------------------------------
(7-a)(a^2+7a+49)
=7a^2+49a+343-a^3+7a^2-49a
= -a^3+14a^2+343

------------------------------------
-16s^2+24s-9
= -(4x-3)^2