Q. If 10x+5y=−8 and −7x−10y=−9 are true equations, what would be the value of 3x−5y ?Answer:
Given Equations: We are given two equations:10x+5y=−8 (Equation 1)−7x−10y=−9 (Equation 2)We need to find the value of 3x−5y.First, let's try to eliminate one of the variables by multiplying Equation 2 by 0.5 to make the coefficients of y the same.
Eliminate Variable: Multiply Equation 2 by 0.5: 0.5×(−7x−10y)=0.5×(−9)This gives us:−3.5x−5y=−4.5 (Equation 3)Now we have the y coefficients the same in both Equation 1 and Equation 3.
Add Equations: Add Equation 1 and Equation 3 to eliminate y:(10x+5y)+(−3.5x−5y)=−8+(−4.5)This simplifies to:10x−3.5x=−8−4.56.5x=−12.5Now we can solve for x.
Solve for x: Divide both sides by 6.5 to solve for x: 6.56.5x=6.5−12.5x=6.5−12.5x=−1.92307692308 (approximately)Now we have the value of x.
Solve for y: Substitute the value of x back into Equation 1 to solve for y:10(−1.92307692308)+5y=−8−19.2307692308+5y=−8Add 19.2307692308 to both sides to solve for y:5y=−8+19.23076923085y=11.2307692308Now divide by 5 to get the value of y:y=511.2307692308y=2.24615384616 (approximately)
Find 3x−5y: Now that we have both x and y, we can find the value of 3x−5y:3(−1.92307692308)−5(2.24615384616)=−5.76923076924−11.2307692308=−17.00000000004 (approximately)However, we should expect an exact value since we are dealing with linear equations. There might be a rounding error due to the approximation of x and y. Let's re-evaluate the calculations without rounding.
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