プリントゆうえんち 解説 問題1・2 問題1・2解答 問題3〜6 問題3〜6解答
次の場合の変化の割合を |
比で |
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別解で |
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もっと簡単な別解で |
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解いてみよう。 |
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(グラフも自分でかいてみよう。) |
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(問題3) |
関数 |
y= |
1 |
x |
2 |
で、x が−6から3まで増加するとき |
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3 |
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y の値を確認 |
… |
x=-6のとき→ |
y= |
1 |
x |
2 |
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1 |
× |
(- 6) |
2 |
= |
12 |
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3 |
3 |
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y |
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12 |
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x=3のとき→ |
y= |
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x |
2 |
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× |
3 |
2 |
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3 |
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3 |
3 |
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3 |
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x |
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比で |
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1:x =9: −9 |
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9x=−9 |
x=−1 |
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-6 |
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0 |
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3 |
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(答え) |
変化の割合は −1 |
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別解で |
変化の割合= |
( y の増えた量) |
= |
3−12 |
= |
-9 |
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-1 |
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( x の増えた量) |
3−(−6) |
9 |
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もっと簡単な別解で |
変化の割合= |
1 |
(−6+3) |
= |
1 |
× |
(-3) |
= |
-1 |
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3 |
3 |
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(問題4) |
関数 |
y= |
2 |
x |
2 |
で、x が−2から4まで増加するとき |
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y の値を確認 |
… |
x=−2のとき→ |
y = |
2 |
x |
2 |
= |
2 |
× |
(- 2) |
2 |
= |
8 |
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x=4 のとき→ |
y = |
2 |
x |
2 |
= |
2 |
× |
4 |
2 |
= |
32 |
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y |
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32 |
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比で |
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1:x =6: 24 |
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6x=24 |
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x=4 |
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(答え) |
変化の割合は 4 |
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8 |
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x |
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別解で |
変化の割合= |
( y の増えた量) |
= |
32−8 |
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24 |
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4 |
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-2 |
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0 |
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4 |
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( x の増えた量) |
4−(−2) |
6 |
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もっと簡単な別解で |
変化の割合= |
2(−2+4)=2×2= |
4 |
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(問題5) |
関数 |
y= |
−2 |
x |
2 |
で、x が−2から4まで増加するとき |
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y の値を確認 |
… |
x=−2のとき→ |
y = |
-2 |
x |
2 |
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-2 |
× |
(- 2) |
2 |
= |
-8 |
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-2 |
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0 |
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4 |
x |
x=4 のとき→ |
y = |
-2 |
x |
2 |
= |
-2 |
× |
4 |
2 |
= |
-32 |
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-8 |
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比で |
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1:x =6: −24 |
6x=−24 |
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x=−4 |
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-32 |
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(答え) |
変化の割合は −4 |
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別解で |
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変化の割合= |
( y の増えた量) |
= |
-32−(-8) |
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-24 |
= |
-4 |
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( x の増えた量) |
4−(−2) |
6 |
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もっと簡単な別解で |
変化の割合= |
−2(−2+4)=−2×2= |
−4 |
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(問題6) |
関数 |
y= |
−2 |
x |
2 |
で、x が−3から1まで増加するとき |
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y の値を確認 |
… |
x=−3のとき→ |
y = |
-2 |
x |
2 |
= |
-2 |
× |
(- 3) |
2 |
= |
-18 |
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0 |
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1 |
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x |
x=1 のとき→ |
y = |
-2 |
x |
2 |
= |
-2 |
× |
1 |
2 |
= |
-2 |
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-2 |
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比で |
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1:x =4: 16 |
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4x=16 |
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x=4 |
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-18 |
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(答え) |
変化の割合は 4 |
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別解で |
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変化の割合= |
( y の増えた量) |
= |
-2−(-18) |
= |
16 |
= |
4 |
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( x の増えた量) |
1−(−3) |
4 |
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もっと簡単な別解で |
変化の割合= |
−2(−3+1)=−2×(−2)= |
4 |
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