Question 58

Select the number that will come in place of the question mark (?) in the following mathematical statement.
$$49 \times 57 - 41 \times 18 = (?)^{2} \times 3 + 1380$$

Solution

$$49\times\ 57\ -\ 41\times\ 18=\left(x^2\right)\times\ 3\ +\ 1380$$

$$2793\ -\ 738=x^2\times\ 3\ +\ 1380$$

$$2055=3x^2+1380$$

$$2055-1380=3x^2$$

$$675=3x^2$$

$$\frac{675}{3}=x^2$$

$$225=x^2$$

$$x^{ }=\sqrt{\ 225}$$

$$x^{ }=15$$

Hence option A is the correct answer

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