<例題>次の計算をしなさい。
1) (27)0.5−7×60.5/20.5+20.5×20.5 (高専)
2) {3−(27)0.5}/30.5
+(−12/50.5)÷(7.2)0.5
−30.5(40.5−(12)0.5) (成城高)
3) {(60.5+50.5)/20.5}2
−(60.5+50.5)(60.5−50.5)
+{(60.5−50.5)/20.5}2 (日比谷)
<解答>1)(27)0.5−7×60.5/20.5+20.5×60.5
=3×30.5−7×30.5+2×30.5
=(3−7+2)×30.5
=−2×30.5
2){3−(27)0.5}/30.5
+(−12/50.5)÷(7.2)0.5
−30.5(40.5−(12)0.5)
={3−3×30.5}/30.5
+(−12/50.5)÷(72/10)0.5
−30.5(2−2×30.5)
={30.5−3}+(−12/50.5)÷(36/5)0.5−2×30.5+6
={30.5−3}+(−12)÷(36)0.5−2×30.5+6
={30.5−3}−2−2×30.5+6
=1−30.5
3){(60.5+50.5)/20.5}2
−(60.5+50.5)(60.5−50.5)
+{(60.5−50.5)/20.5}2
=(60.5+50.5)2/2−(6−5)+(60.5−50.5)2/2
=(60.5+50.5)2/2+(60.5−50.5)2/2−1
=(6+2×60.5×50.5+5)/2
+(6−2×60.5×50.5+5)/2−1
=(6+5)/2+(6+5)/2−1
=10
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