Răspuns:
Explicație pas cu pas:
1.
a) x^2 = 7
x1 = √7
x2 = -√7
b) 2x^2 = 98
x^2 = 49
x1 = 7
x2 = -7
c) x^2 + 2 = 0 nu are solutii reale
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2.
5(x - 2)^2 = 69 - 24 = 45
(x - 2)^2 = 45 : 5 = 9
x - 2 = 3; x = 5
x - 2 = -3; x = -1
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3.
1 + 1 + 0^2 = 2
2 = 2 adevarat
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4.
1 + 3 + 5 + .... + 101
an = a1 + (n - 1)r
101 = 1 + (n - 1)*2 = 1 + 2n - 2 = 2n - 1
2n = 102
n = 51
1 + 3 + 5 + .... + 101 = 51*(1 + 101)/2 = 51*102/2 = 51*51
x^2 = 51^2
x1 = 51; x2 = -51
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5.
4x^2 + 12 = 16x^2 - 36
48 = 12x^2
x^2 = 4
x1 = 2
x2 = -2
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6.
A = 576 cm^2
A = L^2
L = √576 = 24 cm
