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7^(x+1) + 7^x + 7^(x-1) = 399, what is x? Could someone help me with these math problems? I can't figure them out. Solve the linear equation;
x+2y=15
y=-2x+0 9x-12y=-3
-12x+16y=4? 15.00g of Si reacts with 25.00g of F2 to produce 28.67g of SiF4. Which reactant is the limiting reagent? What can you tell me about the flower of life? Sacred geometry? Where does it come from? Make a conjecture about the next item in the sequence.1, -4, 9, -16,?