What some things that apply to quadratics
1 answer:
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Answer:
Step-by-step explanation:
Hello,
(1) 2x + 4y + z = 3
(2) x - 2y - 3z = 4
(3) x + y - z = -1
From (3) we can write z = x + y + 1 and we replace in (1)
2x + 4y + x + y + 1 = 3 <=> 3x + 5y = 3-1 =2
(1') 3x + 5y = 2
and we replace in (2)
x - 2y -3(x+y+1) = 4 <=> -2x -5y -3 = 4 <=> -2x -5y = 4 + 3 = 7
(2') -2x - 5y = 7
(1') + (2') gives
3x - 2x + 5y - 5y = 2 + 7 = 9
x = 9
we replace in (1')
3*9 + 5y = 2 <=> 27 + 5y = 2 <=> 5y = 2-27 = -25 <=> y = -25/5 = -5
y = -5
and then in (3)
9 - 5 - z = -1 <=> 4 - z = -1 <=> z = 4 + 1 = 5
z = 5
hope this helps
Answer:
Step-by-step explanation:
Area of outer triangle =
= 2x*4x + 2x*3
= 8x² + 6x
Area of inner triangle=
Area of aluminium = area of outer triangle - area of inner triangle
= 8x² + 6x + 2x² + 5x
= 10x² + 11x
Area of 20 aluminum borders = 20*(10x² + 11x) = 200x² + 220x
b) x = 25 cm
Area of 20 aluminum borders = 200*25² + 220*25
= 200 * 625 + 220*25
= 125000 + 5500
= 130500 cm²
c) Area of inner triangle (Glass) = 5500 cm²
Cost of aluminium = 130500 * 0.06 = $ 7830
Cost of glass = 5500 * 0.03 = $ 165
Cost of making 20 windows = 7830 + 165 = $ 7995