Answer:

Step-by-step explanation:
Since angle RTS is a right angle, we have three similar triangles.
Thus, 
Cross Products, 
Take the square root: 
(7x^2-3x)+4x^2
7x^2+4x^2-3x
11x^2-3x
Answer: 11x^2-3x.
You just combine like terms.
Answer:
The first blank is 81
+9=x-1
The second blank is 9x+3=x^2-1
Step-by-step explanation:
For the first part, you must set up the equation (9x+3)^2 then you must multiply the exponent to the inside exponents
+
next, simplify.
81
+9=x-1
For part two, set up equation.
Then simplify 9x+3= 
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