To solve these trigonometric equations, we need to use trigonometric identities and algebraic manipulation to simplify the equations and find the values of x that satisfy them.

Let's start with the first equation:

sinx - √2 sin3x = -sin5x

We can use the sum-to-product identity for sine to rewrite sin3x as sinx cos2x + cosx sin2x. This will allow us to rewrite the equation in terms of sinx and cosx, which will make it easier to solve.

sinx - √2 (sinx cos2x + cosx sin2x) = -sin5x

Simplify the equation by expanding the terms:

sinx - √2 sinx cos2x - √2 cosx sin2x = -sin5x

Now, we can combine the terms with sinx and rearrange the equation:

sinx(1 - √2 cos2x) = -sin5x + √2 cosx sin2x

We can then use trigonometric identities to simplify the equation further. Let's move to the second equation:

cos(70° + x)cos(x - 20°) = 1/2

Use the angle addition formula for cosine to expand the left side of the equation:

[cos70°cosx - sin70°sinx][cosxcos20° + sinxsin20°] = 1/2

Simplify the expression by expanding and combining terms:

cos70°cosx cosxcos20° + cos70°cosx sinxsin20° - sin70°sinx cosxcos20° - sin70°sinx sinxsin20° = 1/2

Now, use trigonometric identities to simplify the equation further.

After simplifying and solving the equations, we will be able to find the values of x that satisfy both equations. Let me know if you need further help in solving these equations.