Use elimination to solve the system for 4x + 7 y equals -14 + 8 x + 5 y equals 8 for x
1 answer:
9514 1404 393
Answer:
(x, y) = (3.5, -4)
Step-by-step explanation:
Elimination is easiest if one of the coefficients of a variable is a multiple of the other coefficient of the variable. Here, we have x-coefficients of 4 and 8, so it will be easiest to eliminate x.
Subtract the second equation from 2 times the first.
2(4x +7y) -(8x +5y) = 2(-14) -(8)
9y = -36 . . . . . simplify
y = -4 . . . . . . . divide by 9
4x +7(-4) = -14 . . . . substitute for y in the first equation
4x = 14 . . . . . . . add 28
x = 3.5 . . . . divide by 4
The solution is (x, y) = (3.5, -4).
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4x + 2y = 8 (1)
8x + 4y = -4y (2)
A) Two lines are parallel if they have the same gradient
- putting both equations into the gradient- intercept form ( y = mx + c where m is the gradient)
(1) 4x + 2y = 8
2y = 8 - 4x
y = -2x + 4
(2) 8x + 4y = -4y
<span> </span>8x = -4y - 4y
y =
y = -x
<span>Thus the gradient of the two equations are different and as such the two lines are not parallel
</span>
B) When two lines are perpendicular, the product of their gradient is -1
p = (-2) * (-1)
p = 2
<span> ∴ the two lines are not perpendicular either.</span>
Thus these lines are SKEWED LINES
8x + 4y = -4y (2)
A) Two lines are parallel if they have the same gradient
- putting both equations into the gradient- intercept form ( y = mx + c where m is the gradient)
(1) 4x + 2y = 8
2y = 8 - 4x
y = -2x + 4
(2) 8x + 4y = -4y
<span> </span>8x = -4y - 4y
y =
y = -x
<span>Thus the gradient of the two equations are different and as such the two lines are not parallel
</span>
B) When two lines are perpendicular, the product of their gradient is -1
p = (-2) * (-1)
p = 2
<span> ∴ the two lines are not perpendicular either.</span>
Thus these lines are SKEWED LINES