Here's the solution to your problems:
6. Solve for x in 22x−18×2x=40
Step 1: Rewrite the equation using exponent rules.
We know that 22x=(2x)2.
So the equation becomes:
(2x)2−18×2x=40
Step 2: Introduce a substitution to form a quadratic equation.
Let y=2x. Substitute y into the equation:
y2−18y=40
Step 3: Rearrange the equation into standard quadratic form and solve for y.
y2−18y−40=0
Factor the quadratic equation:
(y−20)(y+2)=0
This gives two possible values for y:
y−20=0⟹y=20
y+2=0⟹y=−2
Step 4: Substitute back 2x for y and solve for x.
Case 1: y=20
2x=20
Take the logarithm of both sides (e.g., base 10 or natural log):
log(2x)=log(20)
xlog(2)=log(20)
x=log(2)log(20)
Using a calculator:
x≈0.301031.30103≈4.3219
Case 2: y=−2
2x=−2
An exponential function with a positive base, like 2x, is always positive for real values of x. Therefore, there is no real solution for x in this case.
The only real solution for x is:
x=log(2)log(20)≈4.3219
7. Given that Sin(x−30)0−Cos(4x)0=0. Find the tan(2x+30)0
Step 1: Rearrange the given equation.
Sin(x−30)0=Cos(4x)0
Step 2: Use the trigonometric identity Sin(θ)=Cos(900−θ).
This means that the angles must be complementary (or differ by multiples of 3600, but for basic problems, we assume the simplest case).
So, we can equate the angles:
(x−30)0+(4x)0=900
Step 3: Solve for x.
x−30+4x=90
5x−30=90
5x=90+30
5x=120
x=5120
x=24
Step 4: Substitute the value of x into the expression tan(2x+30)0.
First, calculate the angle:
2x+30=2(24)+30
2x+30=48+30
2x+30=78
Now, find the tangent of this angle:
tan(78)0
Using a calculator:
tan(78)0≈4.7046
The value is:
tan(2x+30)0≈4.7046
3 done, 2 left today. You're making progress.