Solve the simultaneous equations x-6y=5 xy - 2y2 = 6 - Show clear algebraic working.
2 answers:
Answer:
(- 7, - 2 ) , (9.5, 0.75 )
Step-by-step explanation:
Given the equations
x - 6y = 5 ( add 6y to both sides )
x = 5 + 6y → (1)
xy - 2y² = 6 → (2)
Substitute x = 5 + 6y into (2)
(5 + 6y)y - 2y² = 6 ← distribute and rearrange left side
5y + 6y² - 2y² = 6
4y² + 5y = 6 ( subtract 6 from both sides )
4y² + 5y - 6 = 0 ← in standard form
(y + 2)(4y - 3) = 0 ← in factored form
Equate each factor to zero and solve for y
y + 2 = 0 ⇒ y = - 2
4y - 3 = 0 ⇒ 4y = 3 ⇒ y = = 0.75
Substitute these values into (1) for corresponding values of x
y = - 2 : x = 5 + 6(- 2) = 5 - 12 = - 7 ⇒ (- 7, - 2 )
y = 0.75 : x = 5 + 6(0.75) = 5 + 4.5 = 9.5 ⇒ (9.5, 0.75 )
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Answer:
Therefore the dimensions of the square should be 0.1528 inch by 0.1528 inch so, the box has largest volume.
Step-by-step explanation:
Given that,
A box is being created out of a 15 inches by 10 inches sheet of metal.
The length of the one side of the squares which are cut out of the each corners of the metal sheet be x.
The length of the metal box be = (15-2x) inches.
The width of the metal box be =(10-2x) inches
The height of the metal box be =x inches
Then, the volume of the metal box= length×width×height
=(15-2x)(10-2x)x cubic inches
=(150x-50x²+4x³) cubic inches
∴ V= 4x³-50x²+15x
Differentiating with respect to x
V'=12x²-100x+15
Again differentiating with respect to x
V''=24x-100
For maximum or minimum value, V'=0
12x²-100x+15=0
Apply quadratic formula , here a=12, b= -100 and c=15
For x= 8.18, The value of (15-2x) and (10-2x) will negative.
∴x=0.1528 .
Now,
∴At x=0.1528 inch, the volume of the metal box will be maximum.
Therefore the dimensions of the square should be 0.1528 inch by 0.1528 inch so, the box has largest volume.