基礎問
260 演習問題の解答 (①~⑩)
演習問題の解答
ここで、>
1
与式 = (x*y2)x(2xy²)×(-)
2
==
4+1+3,,2+2+3
=-2x³y7
2A-B
=2(x²-2x+3)-(2x²+4x-2)
=(2x²-2x²)+(-4x-4x)+(6+2)
=-8x+8
A-2B
=(x²-2x+3)-2(2x²+4x-2)
=(x²-4x²)+(-2x-8x)+(3+4)
=-3x²-10x+7
3
(1)s=x-y,t=z-w とおくと
(x-y-z+w)(x−y+z-w)
=(s-t)(s+t)=s²- t²
=(x
=x²+x-(y2-5y+6)
= x²+x-(y-2)(y-3)
={x+(y−2)}{x-(y-3)}
=(x+y-2)(x-y+3)
2
よって
(3) a²(b-c)+b²(c-a)+c²(a-b)
=(b-c)a²-(b²-c²)a+b²c-c²b
=(b-c)a²-(b−c)(b+c)a
+bc(b-c)
=(b-c){a²-(b+c)a+bc)
=-(a-b)(b-c)(c-a)
(4) (x+1)(x+2)(x+3)(x+4)-24
={(x+1)(x+4)}{(x+2)(x+3)}-24
=(x+5r+4)(r+5r+6)–24
=(x+5r)2+10(r+5r)
=(x²+5x)(x2+5x+10)
=x(x+5)(x+5r+10)
(5) x²+2x²+9
=(x²+6x²+9)−4x²
=(x²+3)²-(2r)²
6
0.769230
13) 10.0
91
90
78
120
117
30
26
4