ページ3:

自学© Akagi
1 [文字式の計算】
(1) 3x+8y+2x-7y
=3x+2x+8y-7y
=5x+y
(3) (m−4n)+(6m+2n)
= m - 4n+ 6m + 2n
= 7m - 2n
(5) (-2a)x(-7b)
=
+(2×7)ab
= 14ab
(2) 4x²-x-5x-3x²
2
= 4x²-3x²-x-5x
2
= x²-6x
(4) (5x-3y)-(9x - y)
= 5x − 3 y − 9x + y
-
= -4x-2y
(6) 42xy÷(-6x)
42xy
6x
= -7 y

ページ4:

#CAkagi
〖単項式・多項式の計算〗
(7) (-
a
-
3
-b)x24
4
3
(8) (12x-9y)÷3
=
12x 9y
6
=1/2x24-12/26×24
==
= 4a-18b
(9) 2(3a-b)+4(-2a+3b)
=
= 6a - 2b - 8a +12b
= -2a+10b
3
3
=4x-3y
x-2y 2x+y
(10)
4
10
5(x-2y)-2(2x+y)
20
5x-10y-4x-2y
20
x-12y
20
(11) 18a³b² ÷ (-3a)²
18a3b2
9a²
(12) 12x²y÷3y÷
= 12x² y×
1
2
1
2
3y x
=
2ab2
= = 4x

ページ5:

自学 © Akagi
2 【文字式の利用】
(1) アエ
(2)
(x-2y)-(4x-6y) =x-2y-4x + 6y
=-3x+4y
3
=-3×(-2)+4×
4
= 9
(3) もとの半円の周の長さ
2πr÷2+2r=πr+2r
半径を2cm長くした半円の周の長さ
…①
2π(r + 2) +2 + 2(r + 2) = πr +2 +2r+4 …②
② - ① より
(2+4)cm