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SAT - Math - Algebra

If a= 5 sqrt(2) and 2a = sqrt(2x), what is the value of x (more)

If a= 5 (2) and 2a =(2x), what is the value of x

Given:

a= 5 √(2) and 2a =√(2x)

 

i.e.

2*5√2 = √2x

squaring both sides

4*25*2 = 2x

x = 100

If x-1/3 = k and k=3, what is the value of x? (more)

If x-1/3 = k and k=3, what is the value of x?

x - 1/3 = k where k =3

x - 1/3 = 3

x = 3 + 1/3 = 10/3

x + y = -9; x + 2y = -25 According to the system of equations above, what is the value of x? (more)

x y = -9;

x 2y = -25

According to the system of equations above, what is the value of x?

x + y = -9 ... (1)

x + 2y = -25 ... (2)

2* equation 1 - equation 2

2x + 2y - x - 2y = -18 + 25

x = 7

 

If 5x + 6 = 10, what is the value of 10x + 3 ? (more)

If 5x 6 = 10, what is the value of 10x 3 ?

5x + 6 = 10

5x = 4

x = 4/5

therefore, 10x + 3 = 10*4/5 + 3 = 8 + 3 = 11

If x is positive and f(x) = x(x+1) and f(k+5) = 72. What is k? (more)

If x is positive and f(x) = x(x 1) and f(k 5) = 72. What is k? 

f(x) = x (x + 1)

f(k + 5) = (k + 5)*(k +6) = k2 + 11k + 30 = 72

k2 + 11k - 42 = 0

k2 + 14k - 3k - 42 = 0

(k+14) (k-3) = 0

k = 14 or 3