$$\left(t + x\right) \left(t + 3 x\right)$$
The perfect square
Let's highlight the perfect square of the square three-member
$$3 x^{2} + \left(t^{2} + 4 t x\right)$$
Let us write down the identical expression
$$3 x^{2} + \left(t^{2} + 4 t x\right) = - x^{2} + \left(t^{2} + 4 t x + 4 x^{2}\right)$$
or
$$3 x^{2} + \left(t^{2} + 4 t x\right) = - x^{2} + \left(t + 2 x\right)^{2}$$
in the view of the product
$$\left(- \sqrt{1} x + \left(t + 2 x\right)\right) \left(\sqrt{1} x + \left(t + 2 x\right)\right)$$
$$\left(- x + \left(t + 2 x\right)\right) \left(x + \left(t + 2 x\right)\right)$$
$$\left(t + x \left(-1 + 2\right)\right) \left(t + x \left(1 + 2\right)\right)$$
$$\left(t + x\right) \left(t + 3 x\right)$$
General simplification
[src]
$$t^{2} + 4 t x + 3 x^{2}$$
Rational denominator
[src]
$$t^{2} + 4 t x + 3 x^{2}$$
Assemble expression
[src]
$$t^{2} + 4 t x + 3 x^{2}$$
$$t^{2} + 4 t x + 3 x^{2}$$
$$t^{2} + 4 t x + 3 x^{2}$$
$$\left(t + x\right) \left(t + 3 x\right)$$
Combining rational expressions
[src]
$$t \left(t + 4 x\right) + 3 x^{2}$$
$$t^{2} + 4 t x + 3 x^{2}$$