Question 88

If $$x-y=7$$ and $$x + y = 13$$, then $$x^2 - y^2$$ is

Solution

Equation 1 : $$x - y = 7$$

Equation 2 : $$x + y = 13$$

Adding both equations, we get : $$2x = 7 + 13 = 20$$

=> $$x = \frac{20}{2} = 10$$

Substituting value of 'x' in equation 1, => $$y = 10 - 7 = 3$$

To find : $$x^2 - y^2 = (10^2 - 3^2)$$

= $$100 - 9 = 91$$

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