If - 4x + 6y = 9 and -2x – 7y = -8 are true equations, what would be the value of -2x + 13y?
1 answer:
Answer:
17
Step-by-step explanation:
The expression of interest is the difference of the two given expressions.
(-4x +6y) -(-2x -7y) = (9) -(-8)
-2x +13y = 17
The value is 17.
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<em>Additional comment</em>
You could go to the trouble to solve the two equations for x and y, then compute the value of the expression you want. As we saw above, that is not necessary.
The first step in problem solving is always "look at the given information and how it relates to what you are asked." A little time spent doing that can save a lot of effort in the actual problem solving process.
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Answer:
The first listed equation is the correct equation to solve
The correct answer is: t = 5 seconds
Step-by-step explanation:
Let me mention first that there is an error in the statement that the gravitational pull of the Earth is 16 ft/s^2. It is in fact 32 ft/s^2, and the actual equation uses half of the acceleration multiplied by the square of the variable time, so it gives as final expression :
and we want to find the value/s for "t" that make this equation equal zero (when it reaches the ground and the object just touches the ground. This makes the equation we want to solve:
which solving for "t" becomes:
So we adopt the positive answer (positive time) since the negative value has no physical meaning for this problem.
That is: t = 5 seconds