5x - 3y = 10
x + y = 7......multiply by -5
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5x - 3y = 10
-5x - 5y = -35 (result of multiplying by -5)
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-8y = -25
y = 25/8
x + y = 7
x + 25/8 = 7
x = 7 - 25/8
x = 56/8 - 25/8
x = 31/8
solution is (31/8 , 25/8)
Cos(A-B) = cosAcosB + sinAsinB
<span>
cos(</span>π/2 - θ) = cos(π/2)cosθ + sin(π/2)sinθ
π/2 = 90°
cos(π/2) = cos90° = 0. sin(π/2) = sin90° = 1
cos(π/2 - θ) = cos(π/2)cosθ + sin(π/2)sin<span>θ
</span>
= 0*cosθ + 1*sin<span>θ = </span>sin<span>θ
Therefore </span>cos(π/2 - θ) = sin<span>θ
QED </span>
Answer:
-50x^2+30x-4
Step-by-step explanation:
