This can be solved easily using a Calculator . We get the answer as color(green)(approx 21.400935≈21.400935
But if we are expected to do it without a calculator , here's how it can be done.
sqrt458 = sqrt(2*229) = sqrt 2 * sqrt 229√458=√2⋅229=√2⋅√229
We know that sqrt 2 approx 1.4142√2≈1.4142
To find the color(blue)(sqrt229√229, we can use the following formula:
sqrt(Non-Perfect-Square) approx sqrt(Nearest-Perfect-Square) + (Deviation)/(2*sqrt(Nearest-Perfect-Square))√Non−Perfect−Square≈√Nearest−Perfect−Square+Deviation2⋅√Nearest−Perfect−Square
The nearest perfect square to 229 is 225225. And the deviation is 229 - 225 = 4229−225=4
sqrt 229 approx sqrt 225 + (4)/(2*sqrt225)√229≈√225+42⋅√225
approx 15 + (4/30) approx color(blue)(15.133≈15+(430)≈15.133
Hence we get sqrt458 approx 1.4142 * 15.133 approx color(green)(21.4015√458≈1.4142⋅15.133≈21.4015