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3x-1 plus 7 equals 7x-2x plus x?
(3x - 1) + 7 = (7x - 2x) + x3x - 1 + 7 = 7x - 2x + x3x + 6 = 6x6 = 3xx = 6/3 = 2
How do you solve the following simultaneous equations by elimination 3x-2y equals 11 and X plus 2y equals 9?
All you need to do on these is make the coefficient(number) of either variable the same, usually by multiplication, then add or subtract to eliminate that variable.Using YAs the coefficients of Y are the same, just add the equations:3x - 2y = 11x + 2y = 9--------------4x + 0y = 204x = 20 , which means X = 5 and Y =2Using X3x - 2y = 11x + 2y = 9Multiply the second equation by 3 and subtract.x + 2y = 9 becomes 3x + 6y = 27, and it is easiest to just subtract the first3x + 6y = 27- (3x - 2y = 11)------------------0x +8y = 168y = 16 so Y = 2 and X = 5
How many 3 digit numbers contain the digit 3 at least once?
To find the number of 3-digit numbers that contain the digit 3 at least once, we can use the concept of complementary counting. There are a total of 900 three-digit numbers (ranging from 100 to 999). To find the numbers that do not contain the digit 3, we calculate the numbers with digits 0, 1, 2, 4, 5, 6, 7, 8, and 9 in each place. There are 8 choices for each place, so the total number of three-digit numbers without the digit 3 is 8 x 9 x 9 = 648. Therefore, the number of three-digit numbers that contain the digit 3 at least once is 900 - 648 = 252.
