Răspuns:
[tex]a)13 + 133 \times 2 - 131 \times 2 = \\ = 13 + 2 \times (133 \times 1 - 131 \times 1) = \\ = 13 + 2 \times (133 - 131) = \\ = 13 + 2 \times 2 = 13 + 4 = 17[/tex]
[tex]b)15 \times 16 + 15 \times 27 - 32 \times 15 = \\ = 15 \times (16 + 27 - 32) = \\ = 15 \times (43 - 32) = \\ = 15 \times 11 = 165[/tex]
[tex]d)68 + 7 \times 68 + 68 \times 5 - 12 \times 68 = \\ = 68 \times (1 + 7 + 5 - 12) = \\ = 68 \times (13 - 12) = \\ = 68 \times 1 = 68[/tex]
[tex]e) {7}^{45} \times {7}^{23} \div {( {7}^{33} })^{2} - {234}^{3} \div {78}^{3} = \\ = {7}^{45 + 23} \div {7}^{33 \times 2} - ( {234 \div 78)}^{3} = \\ = {7}^{68} \div {7}^{66} - {3}^{3} = \\ = {7}^{68 - 66} - 27 = \\ = {7}^{2} - 27 = 49 - 27 = 22[/tex]
[tex]f)1 + 2 + 3 + ... + 500 = \\ = \frac{500 \times (500 + 1)}{2} = \\ = \frac{500 \times 500 + 500 \times 1}{2} = \\ = \frac{250000 + 500}{2} = \frac{250000}{2} + \frac{500}{2} = 125000 + 250 = 125250[/tex]
[tex]c)6 \times (11 + 99 \div (7 + 13 \times 2) - 4 \times {3}^{2} = \\ = 6 \times (11 + 99 \div (7 + 26) - 4 \times 9 = \\ = 6 \times (11 + 99 \div 33) - 36 = \\ = 6 \times (11 + 3) - 36 = \\ = 6 \times 14 - 36 \\ = 84 - 36 = 48[/tex]
