X = 3
y = - 2
Получаем систему уравнений:
3a + (- 2b) = 4
3b - (- 2a) = 7
3a - 2b = 4; => 3a = 4 + 2b; => a = (4 + 2b) : 3.
3b + 2a = 7; => 2a = 7 - 3b; => a = (7 - 3b) : 2.
(4 + 2b) : 3 = (7 - 3b) : 2
2(4 + 2b) = 3(7 - 3b)
8 + 4b = 21 - 9b
4b + 9b = 21 - 8
13b = 13
b = 1
a = (4 + 2 * 1<span>) : 3 = 2
</span>
Ответ: a = 2; b = 1.
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4cos²x+4cos(π/2+x)-1=0
4cos²x-4sinx-1=0
4(1-sin²x)-4sinx-1=0
4-4sin²x-4sinx-1=0
4sin²x+4sinx-3=0
sinx=y
4y²+4y-3=0
D=4²-4*4*(-3)=16+48=64=4²
y1=(-4+4)/8=0/8=0
y2=(-4-4)/8=-8/8=-1
sinx=0 sinx=-1
x=πn, n∈Z x=3π/2+2πn, n∈Z
x∈[π;5π/2]
<u>x={π; 3π/2; 2π} </u>