V.- Hállese el valor numérico de una expresión algebraica

A continuación se proponen ejercicios para hallar el valor numérico de expresiones algebraicas, sustituyendo valores en las variables y realizando los cálculos correspondientes.

41.

$\large 3a-ac-bc+ac$

si a=4; b=2; c=1

42.

$\large a(b-c)+b(c-a)$

si a=5; b=12; c=8

43.

$\large x^{3}-x^{2}y+xy^{2}-y^{3}$

si x = 2; y = -1

44.

$\large x^{2}-3x^{2}y+3xy^{2}+y^{3}$

si x = 1; y = 2

45.

$\large a(b+c+d)-bc$

si a = 5; b = 4; c = 4; d = 2

46.

$\large a(3a^{2}-b^{2}+c^{2})+b(b^{2}-c^{2})$

si a = 6; b = -3; c = -2

47.

$\large 8x^{3}-4x^{2}+5x-10$

si x = 2

48.

$\large \frac{b+b'}{2}\: .\: a$

si b = 12; b’ = 8; a = 5

49.

$\large 2\pi Rg$

si R = 8; g = 6

50.

$\large 2\pi Rg$

si R = 4; a = 5

51.

$\large \frac{1}{3}\pi R^{2}a$

si R = 5; a = 6

52.

$\large 5x^{4}+3x^{3}-8x^{2}+6x+4$

si x = -3

53.

$\large 8a^{2}-3ab+5b^{2}$

si a = -2; b = 3

54.

$\large 10a^{3}-8a^{2}b+12ab^{2}-6b^{3}$

si a = -4; b = -5

55.

$\large 12x^{4}+9x^{3}y-5x^{2}y^{2}+6xy^{3}-8y^{4}$

si x = 2/3; y = 5

56.

$\large 4x^{3}-12x^{2}y+8xy^{2}-9y^{3}$

si x = 1/4; y = 1/3

57.

$\large 12ab-5a^{3}+15ab^{2}-24c^{3}+5a^{2}b$

si a = 9; b = 5; c = 3

58.

$\large a(b+c+d)-bc$

si a = 2/3; b = 3/4; c = 5/6

59.

$\large (a-b)[c(a+b)-a(c-b)]$

si a = 6; b = 2; c = 5

60.

$\large 25a^{4}b-4a^{3}b^{2}+8a^{2}b^{3}+16ab^{4}$

si a = 1/5; b = -3/4

61.

$\large (x+y)(x+y)-(x^{2}+y^{2})$

si x = 8; y = 10

62.

$\large (x^{2}+1)^{2}-(x^{2}-1)^{2}+x^{3}$

si x = 3

63.

$\large (x^{2}+1)^{2}-(x^{2}-1)^{2}+x^{3}$

si a = 4; b = 3; c = 5; d = -2

64.

$\large \frac{c^{2}-5a+b}{3a^{2}}$

si a = 6; b = -3; c = -2

65.

$\large 4b^{2}-\sqrt{a-c+1}$

si a = 6; b = -3; c = -2

66.

$\large (b-c)\sqrt{a^{2}+b^{2}+c^{2}}$

si a = 6; b = -3; c = -2

67.

$\large \sqrt{a-12}\: +\: \sqrt{b+5}\: -c^{2}$

si a = 12; b = 20; c = 2

68.

$\large (\frac{a+b}{a-b}-\frac{a-b}{a+b})\: \frac{a}{b}$

si a = 6; b = -3

69.

$\large \frac{3ab}{xy}+\frac{8bc^{2}}{x^{2}}-\frac{9abc}{y^{2}}$

si a = 4; b = 1; c = 5; x = 2; y = 3

70.

$\large \frac{h}{3}(a^{2}+b^{2}+\sqrt{ab})$

si a = 4; b = 5; h = 6

71.

$\large \frac{\pi h}{3}(R^{2}+r^{2}+Rr)$

si π = 3,1416; R = 7; r = 4; h = 9

72.

$\large \sqrt{p(p-a)(p-b)(p-c)}$

si a = 26; b = 28; c = 30; p = 32

73.

$\large \sqrt{a-2}+\sqrt{a+9}\: -5(\frac{-a+\sqrt[3]{a}}{-a\sqrt{2a+10}})$

si a = 27

74.

$\large b[a(b+c)-c^{2}]+(b-c)[b^{2}c+(a-b)]$

si a = 6; b = 4; c = 3

75.

$\large b^{3}-c(a+b+2)+(b-1)[a^{2}-c(a-3)]+ac$

si a = 4; b = 5; c = 3

76.

$\large a^{2}-c^{2}-\frac{3a+\sqrt{b^{2}c+12}-4}{\sqrt{2a^{2}+c^{2}-5}}$

si a=6; b=4; c=3

77.

$\large \frac{a-\frac{3}{4}b^{2}+c}{5a-2b+3c}\: +2b-3$

si a=12; b=2; c=4

79.

$\large \sqrt[3]{2a^{3}+\frac{3b^{2}}{2}}+105c^{3}$

si a=3; b=-1/2; c=-1/4

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