1.3*1.3=x*x+0.4*0.4

Solution for 1.3*1.3=x*x+0.4*0.4 equation:

Simplifying
1.3 * 1.3 = x * x + 0.4 * 0.4

Multiply 1.3 * 1.3
1.69 = x * x + 0.4 * 0.4

Multiply x * x
1.69 = x2 + 0.4 * 0.4

Multiply 0.4 * 0.4
1.69 = x2 + 0.16

Reorder the terms:
1.69 = 0.16 + x2

Solving
1.69 = 0.16 + x2

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '-1x2' to each side of the equation.
1.69 + -1x2 = 0.16 + x2 + -1x2

Combine like terms: x2 + -1x2 = 0
1.69 + -1x2 = 0.16 + 0
1.69 + -1x2 = 0.16

Add '-1.69' to each side of the equation.
1.69 + -1.69 + -1x2 = 0.16 + -1.69

Combine like terms: 1.69 + -1.69 = 0.00
0.00 + -1x2 = 0.16 + -1.69
-1x2 = 0.16 + -1.69

Combine like terms: 0.16 + -1.69 = -1.53
-1x2 = -1.53

Divide each side by '-1'.
x2 = 1.53

Simplifying
x2 = 1.53

Take the square root of each side:
x = {-1.236931688, 1.236931688}