Решите с уравнения (квадратного). 1. сумма двух чисел 24, их произведение 143, найдите числа. 2. периметр прямоугольного треугольника 24, гипотенуза 10, найдите длины катетов.
1. a + b = 24, ab = 143 (x-a)*(x-b) = 0 <-> x = a, b x^2 - (a+b)x + ab = 0 x^2 - 24x + 143 = 0 x = 12 +- √(144 - 143) = {11, 13} a = 11, b = 13
2. a + b + 10 = 24, a^2 + b^2 = 100 a + b = 14, a^2 + 2ab + b^2 = 196, 2ab = 96 a^2 - 2ab + b^2 = 100 - 96 = 4 (a - b)^2 = 4 -> a - b = +- 2 a + b = 14, a - b = 2 -> a = 8, b = 6 a + b = 14, a - b =-2 -> a = 6, b = 8
a + b = 24, ab = 143
(x-a)*(x-b) = 0 <-> x = a, b
x^2 - (a+b)x + ab = 0
x^2 - 24x + 143 = 0
x = 12 +- √(144 - 143) = {11, 13}
a = 11, b = 13
2.
a + b + 10 = 24, a^2 + b^2 = 100
a + b = 14, a^2 + 2ab + b^2 = 196, 2ab = 96
a^2 - 2ab + b^2 = 100 - 96 = 4
(a - b)^2 = 4 -> a - b = +- 2
a + b = 14, a - b = 2 -> a = 8, b = 6
a + b = 14, a - b =-2 -> a = 6, b = 8