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4) 46 x 46 = 50.50 – 8.50 + 16 = 2500 – 400 + 16 = 2116

5) 56 x 56 = 60.60 – 8.60 + 16 = 3600 – 480 + 16 = 3136

6) 66 x 66 = 70.70 – 8.70 + 16 = 4900 – 560 + 16 = 4356

7) 76 x 76 = 80.80 – 8.80 + 16 = 6400 – 640 + 16 = 5776

8) 86 x 86 = 90.90 – 8.90 + 16 = 8100 – 720 + 16 = 7396

9) 96 x 96 = 100.100 – 8.100 + 16 = 10000 – 800 + 16 = 9216

Penjelasan

(a+b)(a+b) = a + 2ab + b
2
2
= a + 4b + 4a.b – (2ab + 4b )+ b
2
2
2
2
= (a+2b)(a+2b) – 2b(a+2b) + b 2

8.2.9 Perkalian dua digit dengan satuan 5

1) 15 x 15 = 20.20 – 5.2.20 + 5.5 = 400 – 200 + 25 = 225
atau

15 x 15 = 20.20 – 10.20 + 25 = 400 – 200 + 25 = 225

2) 25 x 25 = 30.30 – 10.30 + 25 = 900 – 300 + 25 = 625

3) 35 x 35 = 40.40 – 10.40 + 25 = 1600 – 400 + 25 = 1225

4) 45 x 45 = 50.50 – 10.50 + 25 = 2500 – 500 + 25 = 2025

5) 55 x 55 = 60.60 – 10.60 + 25 = 3600 – 600 + 25 = 3625

6) 65 x 65 = 70.70 – 10.70 + 25 = 4900 – 700 + 25 = 4225

7) 75 x 75 = 80.80 – 10.80 + 25 = 6400 – 800 + 25 = 5625

8) 85 x 85 = 90.90 – 10.90 + 25 = 8100 – 900 + 25 = 7525

9) 95 x 95 = 100.100 – 10.100 + 25 = 10000 – 1000 + 25 = 9025

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